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#21
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As regards for *my* personal checklist that says to get a UPS with a
sine wave output, yes, it is unnecessary if all you run from that UPS is your computer. I know the computer power supply will handle stepped wave output. Probably the printer, monitor, scanner, speakers, and modem, too. But eventually you upgrade your system and want a bigger UPS. In my case, I want a quieter one; the 2kVA unit that I have now has a fan that makes anywhere from 35 to 50 dB of noise. Will I toss it because I want one without a fan? No. Will I toss it when the batteries go bad? No, because they are replaceable; I've already replaced them once after 5-1/2 years of use (although I decided to use a bus bar instead of a heavy wire lead) at a cost of $140 for the 2 of them which was a tenth of buying a new unit. Since I'll use it for something else, like my audio/video gear, having a sine wave output is important. It gives me more choices on how to use the UPS other than just with computer gear. And for those of you that like pictures with the explanation: http://www.explan.co.uk/antisurge/modes.shtml But apparently it also depends on which country you live and their wiring standards: http://www.zerosurge.com/HTML/mode2.html http://www.zerosurge.com/HTML/works.html http://www.zerosurge.com/HTML/versus.html In the U.S., the neutral is bonded to earth ground at the service entrance, the only way to have common mode surges is from something inside your house, not from outside. Wouldn't a common mode surge coming at you from outside become a normal mode surge (since it then proceeds only on the [hot] line)? I think all the surge arrestors that I've seen here are mode 1 only (line-to-neutral) because neutral was tied to local ground (earth) at the service entry. No, I don't work for ZeroSurge and didn't know about their products until this thread had me hunting around on surge protection and methods. Their article at http://www.zerosurge.com/HTML/about.html had me grinning because I remember calling the telephone company to report problems. Three times they came out and did their local ring test. No problems. The fourth time, after looking around myself, I stood there while they tested. No problems again using both their test gear and making test calls. Took them to the basement and pointed at the MOV (metal oxide varistor) used across their lines. Replaced it, problem fixed. The problems I experienced were indicative of a high resistance short and I figured the MOV went bad. The MOV has very high resistance (10^9 ohms) at low voltages and passes very little current, but it has very low resistance at high voltages which shunts the surge but only for short-duration impulses. That's why they are rated in Joules (N joules = N amps across 1 ohm for *1 second*). MOVs can burn out with one good surge. Most surge protectors rely on MOVs but these eventually go bad over time after being repeatedly stressed. Several grains of zinc oxide (each with an individual breakdown of 3 volts) are sintered together to make a MOV. Each transient destroys some of those grains which reduces it's level of protection. The more it has protected you, the less it will protect you. The eventual failure is a short circuit (which is why sometimes they'll blow apart) and why a fuse should be used. If not fused, you'll smell when a MOV eventually shorts; it will smell like an electrical fire. If MOVs are not themselves fused or enclosed in a fire retardant, they can start fires (see http://www.smarthome.com/4401.html for a news report). Get a surge protector that has an LED for status to tell if the MOV is still good. The MOV should be [thermally] fuse protected or uses disconnect circuitry to shutoff the surge protector. That surge protector becomes nothing more than an extension cord when (not if) the MOV goes bad. A surge arrestor at the mains that goes bad is worthless, too. I can see how an LED can indicate if a TMOV is still good (http://snurl.com/2824), presuming the thermal element fries before the MOV has overly degraded. I suppose for a MOV you could do a similar setup in using a fuse and tie the LED between them. I've seen users employ surge protectors and UPS'es to protect the computer and forget about the telephone line to their modem or the cable going to their cable modem, especially if an internal modem, or even to their expensive audio gear. Also, to those that extol installing a whole-home surge arrestor (which may incur the expense of an electrician and requires it be your house to toy with), a whole-home surge arrestor is a point-of-entry device suppressing surges stemming from outside sources (utility company problems, transformer switching, etc.) but it won't do anything to suppress the high number of power surges that originate *inside* your house (appliances, projector bulb burnout, motors, air conditioning, etc.). I just saw some white papers regarding the origin of surges but had a problem in IE, had to close a window, and lost all of them. My recollection was that 20% of surges come from outside and 80% come from inside. Your A/C causing a surge is not usually a problem for your computer's power supply, but that huge lathe in an industrial environment is. While I can see the arguments for using a point-of-entry or service-entry surge arrestor for the whole home (if that is really an option for you, like you own that house), that may not eliminate surges generated within the home so I still see value for point-of-use surge protectors. w_tom extols dumping the surge to ground but neglects that data lines and audio equipment use this as their reference so the surges that are getting pummeled into local common can cause data and audio problems. It's a 20-year old spec based on using stand-alone devices and shunting the surges. Surge voltage on the ground wire varies by its length. With all the interconnected devices in computer systems, and if you tie in your audio/video system, too, you will have ground loops. If the surge induced on the safety ground at one computer is 1000V but it is 600V at another computer or printer, the 400V difference can cause disruption, degradation, or damage. Even small surges pumped into the safety ground wire can cause data errors, lockups, or other "weird" problems. -- __________________________________________________ __________ ** Share with others. Post replies in the newsgroup. ** If present, remove all "-nix" from my email address. __________________________________________________ __________ "w_tom" wrote in message ... Let's assume the $500 UPS that operates always from the battery. AC mains recharge battery while battery runs inverter (AC power) into computer. But again, one must first understand, electrically, what a surge is. Destructive surges are common mode. Common mode transients cannot be absorbed by that battery. A common mode transient appears equally on both sides of battery. Battery sees no transient voltage as transient continues into and damages adjacent appliance. The battery would absorb a differential mode transient. But destructive transient are common mode which means earth ground is essential to provide protection. Earth ground is why the building wide UPS provides effective protection and why the plug-in UPS (any type) cannot provide such protection. Second, safety ground wire that connects AC mains surge directly to computer motherboard. Surge protector circuit on front end of UPS simply shunts that destructive surge onto green safety ground wire to bypasses the UPS & computer power supply. Safety ground wire connects transient directly to computer electronics. This wire that bypasses UPS is a most common source of transients that damage computer modems. Third, we need not see how surges damage by following circuits. Where is the numerical specification for that UPS that claims common mode surge protection? Please cite that specification. In the meantime a long and well proven principle of surge protection remains. This principle has existed and been repeatedly proven since before WWII for good reason. Surge protection is about earthing a surge. A surge protector (even the one inside that UPS that is actually same circuit found in power strip surge protectors) is only as effective as its earth ground. Four, if that more expensive UPS provides galvanic isolation from surge damage, then same galvanic isolation that exists in PC power supplies would provide the protection - making that UPS protection redundant - providing no additional protection. Computer power supplies already have effective protection. But that existing protection assumes the incoming surge will be earthed before it can enter the building. A plug-in UPS provides no additional protection because it does not have that essential 'less than 10 foot' connection to earth ground. Many reasons for why a more expensive UPS may not be better protection. One - common mode transients are not even seen by the battery. Two - surge can bypass the UPS completely using safety ground wire. Three - UPS does not even claim to provide such protection. Four - any protection provided by that UPS already exists in the power supply. Bottom line remains. A surge protector is only as effective as its earth ground. Furthermore, that earthing protection is so inexpensive. Plug-in UPS has no dedicated connection to earth ground in contrast to what a serious building wide UPSes provides. Plug-in UPS avoids any mention of earthing so that customer will not ask embarrassing questions such as, "what about common mode transient protection?". Even dirty (not sinusoidal) power from a step wave UPS does not adversely affect electronics. The one type of electrical 'dirt' that is so destructive is the common mode transient - what a plug-in UPS does not even claim to protect from. Using the 'purer' sine wave provides nothing useful to a computer's life expectancy. Vanguard wrote: In the meantime, a plug-in UPS connects appliance directly to AC mains when not in battery backup mode. So where is the protection? Not from that plug-in UPS. That plug-in UPS serves one primary function - data protection from blackouts and extreme brownouts. Really depends on the UPS that you get. If you get the cheapies that simply shunt the AC from the input to the output, maybe with some line conditioning, then you are still susceptible to line problems depending on how good in the line conditioning). If you get a UPS that generates the output power then you are further protected. If you get a UPS that has an isolating transformer (which has to be huge and heavy because of the current demands and which then by necessity has to generate the output power) then you are the most protected. I also prefer to get one that has a true sinusoidal output. You can get a UPS like you describe just to protect your OS from being shut down hard. You can pay more that provide surge protection and line conditioning. Or you can pay a lot for one that isolates, generates, and provides very clean output. Obviously the best way to determine how well any line protection is working is to get an oscilloscope that you can connect to your PC to record the source of your power. Hey, there's the next that I need. |
#22
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Common mode surge does not become differential once inside
house. It does not because voltage difference remains between wire with surge and earth ground. That common mode surge inside the building is still seeking earth ground, destructively, via appliances. However common mode surges can induce differential mode transients. Those long wires bundled with other wires will induce transients onto those other wires. This is the induced surge - not from electromagnetic fields of a distant CG strike. A plug-in protector tries to earth the common mode surge down safety ground wire. But that long ground wire, bundled with other wires, only induces the transient on those other wires. Just another reason why plug-in protectors are not effective as noted by last paragraph in: http://www.explan.co.uk/antisurge/modes.shtml Zerosurge and its competition Brickwall and Surgex are series mode protectors. Basically just low pass filters. They cannot work like a dam. Surges will simply overwhelm the dam. But they do work well as dikes. Difference: a dam must stop the flow whereas a dike only diverts the flow downstream. For series mode protectors to work, the surge must have a downstream path to earth ground. Series mode protectors will enhance the protection AND should also reduce noise on that circuit. But, they still require the surge to be provided a path to earth ground - and that is what shunt mode protectors do. Shunt mode protectors make a connection to earth ground only during the surge. Second reason why series mode protector require that shunt mode earth ground: the safety ground wire completely bypasses the filter. If surge is not earthed at service entrance, then surge will get to electronics by safety ground wire, unimpeded, right through series mode protector. They forget to mention that part in the Zerosurge summary. Even series mode protectors have this requirement - a surge protector is only as effective as its earth ground. MOVs do wear out with use. They are useless for small, daily transients such as spikes from a turned off switch. But then those spikes are so trivial as to only be called noise. So small that MOVs don't even see the transients. If those daily spikes caused damage, then the homeowner was replacing dimmer switches daily. For audio recording equipment, a series mode protector would keep those noise spikes away from recording equipment. But that noise from switches and motors does not damage electronics. If noise did damage, then we were all replacing clock radios every day - long before the PC even existed. MOV life expectancy is determined by joules. Since most plug-in protectors do not even claim to provide effective protection, they are also undersized - too few joules. As joules increase, the life expectancy of a surge protector increases exponentially. For example if a 345 joule protector (only using as little as 115 joules in protection) were to survive three same size, standard, 8/20 usec surges, then the 1000 joule 'whole house' protector would withstand on the order of 400 same sized transients. Numbers that plug-in manufacturers would rather avoid. Since lightning surges occur typically once every eight years, then a properly sized 'whole house' protector using MOVs will last more than long enough. They just forget to apply numbers when hyping MOV fear in that Zerosurge discussion. If using a 'whole house' protector, then any surge, interior or exterior, is earthed before it can create damage. Nothing inside the house should create a common mode surge. But even if something does, the 'whole house' protector still shunts the common mode transient to earth. Some papers will outrightly confuse. For example, 80% of transients can come from internal sources. IOW a 5 volt noise spike can be generated by an electric motor. If paper is written by an English major, then that 5 volts suddenly transpires into a 500 volt surge! In reality, if anything is creating destructive surges inside a house, then the homeowner is replacing dimmer switches, clock radios, and GFCI (RCD) daily. Appliances only create noise - well below what every household appliance must withstand. Surges come from exterior events. But too many authors on surges have eyes that glaze over as soon as numbers are provided. These people see surge everywhere - which is what plug-in manufacturers live off - misinformation. But lets assume that central air conditioner is generating surges. OK. The surge will immediately take out internal controls, furnace controls, and the house electronic thermostat. But if the air conditioner is creating this surge, then the surge protector must be at the air conditioner - not on everything else inside the building. And since central air is a dedicated circuit, then the 'whole house' protector would eliminate that mythical surge. Air conditioners and other household appliances don't create surges. They create noise - which hypsters of plug-in protectors forget to mention since they don't provide (or learn) numbers. Want to see an example of outright lies because the author probably did not understand fundamental concepts and probably feared numbers? http://www.howstuffworks.com/surge-protector.htm Facts so perverted as to be one long chain of lies. Many who promote surge protector don't even have basic electrical knowledge such as this author. Important for the surge protector to be at the service entrance for exterior common mode surge since those are higher frequency events. That high frequency in lightning generated surges are why the connection to earth ground must be less than 3 meters. At higher frequencies, wire length takes on a whole different characteristic. It is why a line - neutral protector is effective when the connection of line to neutral to earth ground rod is less than 3 meters (and other electrical characteristics such as not inside metallic conduit, no sharp bends, etc). Wire length is critical to where a surge protector is even connected to earth ground. Earth ground too far away all but does not exist - because of electrical characteristics of destructive surges. Your MOV on phone line is why MOVs are no longer used for such protectors. Semiconductors have long since replaced those MOVs. They either work, or become short circuits that tell human to replace them. MOVs have too much capacitance for use on phone lines. However some pathetic plug-in protectors do use MOVs for phone line protection. Your current phone line protector should be semiconductor based as has been standard for about 15 years. And it should be each phone wire, through protector, less than 3 meters to single point ground. Wire to wire protector do comparatively little. LED to indicate a surge protector as good is really nonsense. That LED can report one mode of failure, but cannot report the protector as good. This example from Zerosurge demonstrates the problem. They even removed all MOVs and the indicator light still declared the protector as OK: http://www.zerosurge.com/HTML/movs.html Transients on internal safety ground wires are irrelevant - basically don't exist - if the 'whole house' protector is installed on every incoming utility (or that utility is directly earthed before entering the building). If using internal plug-in protectors, then transients would be induced every where on safety grounds. Described above were induced surges. But then ground loops would use nearby appliances as a path to earth ground because breaker box earth ground is too far away. This is why an adjacent plug-in protector on AC input to a computer can contribute to damage of a modem - even if computer is powered off. That is correct. Adjacent plug-in surge protector completes a circuit to earth ground, destructively via modern. And modems, especially in North America, are most often damaged by AC electric surges. Once a surge has gotten inside the building, then it will find numerous destructive paths. No plug-in protector is going to stop that. In fact plug-in protectors can give that surge more potentially destructive paths to earth ground - such as the above modem example. Can MOVs create a fire? That is what UL1449 2nd Edition is about. Don't know of any ISO equivalent. But then if those 'adjacent to appliance' MOVs were effective, then MOVs are already inside the appliance. Appliances already have effective internal protection. Protection that assumes the 'big' transient - the surge - will be earthed before it can enter the building. Internal protection that makes adjacent plug-in protectors redundant. Internal protection that makes any other appliance generated 'noise' (not surge) irrelevant. Do you need an electrician? Even if plug-in protectors are installed, the electrician would still be necessary to upgrade a house ground. Many homeowners can install these 'whole house' protectors themselves - since it is that easy - and therefore sold in Home Dept. Even plug-in protectors require earth grounds. Older homes are too often missing this connection that is also essential to human safety. In North America, earth ground should be upgraded to, minimally, post 1990 NEC code requirements. Equivalent earthing is necessary throughout the world. That AC electric earth ground must be less than 10 feet from main disconnect (where neutral meets earth ground) and that earth ground (sometimes called GEC). And all other incoming utilities must also connect to that same earth ground. Exampled was a ground loop problem of computer at 1000 volts and printer at 400 volts. These problems are created when single point grounds are not used. Single point grounds that are necessary and provided by 'whole house' protectors. Resulting voltage difference is called ground loops. It is why peripherals connected to a computer should share same receptacle outlet if not same circuit (or ring). These transient voltages occur when the surge is not first earthed at the service entrance. These voltages are not generated by internal equipment. If any household device generates such voltages, then either a surge protector must be permanently connected to that appliance (the absurd solution) or the device must be removed as a threat to human safety. But then that device would remove itself; would self destruct anyway. Devices have more than sufficient internal protection even on interconnected ports IF the major surges are earthed before entering the building. Every incoming utility must either make a direct connection to single point earth ground OR make that connection via a 'whole house' protector. Plug-in protectors only provide surges with more destructive paths to earth ground such as via appliances. Plug-in protectors sell by forgetting to mention critical earthing OR provide any useful numbers. Plug-in protectors want you to not even discuss common mode transients because they are not selling effective protection. They do not even claim to provide common mode surge protection. One fact always remains - a surge protector is only as effective as its earth ground. No way around that fact. Vanguard wrote: As regards for *my* personal checklist that says to get a UPS with a sine wave output, yes, it is unnecessary if all you run from that UPS is your computer. I know the computer power supply will handle stepped wave output. Probably the printer, monitor, scanner, speakers, and modem, too. But eventually you upgrade your system and want a bigger UPS. In my case, I want a quieter one; the 2kVA unit that I have now has a fan that makes anywhere from 35 to 50 dB of noise. Will I toss it because I want one without a fan? No. Will I toss it when the batteries go bad? No, because they are replaceable; I've already replaced them once after 5-1/2 years of use (although I decided to use a bus bar instead of a heavy wire lead) at a cost of $140 for the 2 of them which was a tenth of buying a new unit. Since I'll use it for something else, like my audio/video gear, having a sine wave output is important. It gives me more choices on how to use the UPS other than just with computer gear. And for those of you that like pictures with the explanation: http://www.explan.co.uk/antisurge/modes.shtml But apparently it also depends on which country you live and their wiring standards: http://www.zerosurge.com/HTML/mode2.html http://www.zerosurge.com/HTML/works.html http://www.zerosurge.com/HTML/versus.html In the U.S., the neutral is bonded to earth ground at the service entrance, the only way to have common mode surges is from something inside your house, not from outside. Wouldn't a common mode surge coming at you from outside become a normal mode surge (since it then proceeds only on the [hot] line)? I think all the surge arrestors that I've seen here are mode 1 only (line-to-neutral) because neutral was tied to local ground (earth) at the service entry. No, I don't work for ZeroSurge and didn't know about their products until this thread had me hunting around on surge protection and methods. Their article at http://www.zerosurge.com/HTML/about.html had me grinning because I remember calling the telephone company to report problems. Three times they came out and did their local ring test. No problems. The fourth time, after looking around myself, I stood there while they tested. No problems again using both their test gear and making test calls. Took them to the basement and pointed at the MOV (metal oxide varistor) used across their lines. Replaced it, problem fixed. The problems I experienced were indicative of a high resistance short and I figured the MOV went bad. The MOV has very high resistance (10^9 ohms) at low voltages and passes very little current, but it has very low resistance at high voltages which shunts the surge but only for short-duration impulses. That's why they are rated in Joules (N joules = N amps across 1 ohm for *1 second*). MOVs can burn out with one good surge. Most surge protectors rely on MOVs but these eventually go bad over time after being repeatedly stressed. Several grains of zinc oxide (each with an individual breakdown of 3 volts) are sintered together to make a MOV. Each transient destroys some of those grains which reduces it's level of protection. The more it has protected you, the less it will protect you. The eventual failure is a short circuit (which is why sometimes they'll blow apart) and why a fuse should be used. If not fused, you'll smell when a MOV eventually shorts; it will smell like an electrical fire. If MOVs are not themselves fused or enclosed in a fire retardant, they can start fires (see http://www.smarthome.com/4401.html for a news report). Get a surge protector that has an LED for status to tell if the MOV is still good. The MOV should be [thermally] fuse protected or uses disconnect circuitry to shutoff the surge protector. That surge protector becomes nothing more than an extension cord when (not if) the MOV goes bad. A surge arrestor at the mains that goes bad is worthless, too. I can see how an LED can indicate if a TMOV is still good (http://snurl.com/2824), presuming the thermal element fries before the MOV has overly degraded. I suppose for a MOV you could do a similar setup in using a fuse and tie the LED between them. I've seen users employ surge protectors and UPS'es to protect the computer and forget about the telephone line to their modem or the cable going to their cable modem, especially if an internal modem, or even to their expensive audio gear. Also, to those that extol installing a whole-home surge arrestor (which may incur the expense of an electrician and requires it be your house to toy with), a whole-home surge arrestor is a point-of-entry device suppressing surges stemming from outside sources (utility company problems, transformer switching, etc.) but it won't do anything to suppress the high number of power surges that originate *inside* your house (appliances, projector bulb burnout, motors, air conditioning, etc.). I just saw some white papers regarding the origin of surges but had a problem in IE, had to close a window, and lost all of them. My recollection was that 20% of surges come from outside and 80% come from inside. Your A/C causing a surge is not usually a problem for your computer's power supply, but that huge lathe in an industrial environment is. While I can see the arguments for using a point-of-entry or service-entry surge arrestor for the whole home (if that is really an option for you, like you own that house), that may not eliminate surges generated within the home so I still see value for point-of-use surge protectors. w_tom extols dumping the surge to ground but neglects that data lines and audio equipment use this as their reference so the surges that are getting pummeled into local common can cause data and audio problems. It's a 20-year old spec based on using stand-alone devices and shunting the surges. Surge voltage on the ground wire varies by its length. With all the interconnected devices in computer systems, and if you tie in your audio/video system, too, you will have ground loops. If the surge induced on the safety ground at one computer is 1000V but it is 600V at another computer or printer, the 400V difference can cause disruption, degradation, or damage. Even small surges pumped into the safety ground wire can cause data errors, lockups, or other "weird" problems. |
#23
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I'm not an electrical engineer but find this topic interesting. Could
you please define what you mean by a "common mode" surge. I thought that meant the impulse was on both wires (line and neutral) and that a surge only on 1 wire was a "normal mode" surge. There are probably more technical explanations of common mode signals but the one at http://www.explan.co.uk/antisurge/modes.shtml seems to suffice (if you neglect the resistance to ground which apparently you do in claiming that slamming the surges to ground does not affect data transmission which uses ground as the reference). Say I have a common mode surge headed at my house (same impulse on both wires). At the service entry, the neutral is grounded to earth. Are you saying the impulse on the neutral still continues into the house? Then what was the point of grounding the neutral wire at the service entrance? And wouldn't this disqualify all your arguments regarding shunting the surge to ground if the shunt that already and permanently exists where the neutral wire is bonded to ground at the service entry doesn't work to eliminate the surge? Why would I expect a surge arrestor to do any better than a solid heavy gauge wire in shunting the surge to ground? If the surge is grounded on the neutral wire and doesn't proceed further and only the surge on the [hot] line gets through, why would that still be considered a common mode surge if the [companion] surge is now missing on the neutral wire? Also, do you know of any online links to ANSI, IEEE, and UL specifications (that I don't have to pay for)? As I mentioned, this is not my career but an interest as a result of my career and hobbies (i.e., it's not what I do but it can affect what I do). When I have gone hunting for the specs, it seems I end up as some site that wants me to pay for the documentation. For example, I want to find out about UL1449 referenced by a product, I go to http://www.ul.com and click the link for "Standards", and I get redirected to somewhere else (http://snurl.com/28fb) where I can buy a copy of the standard for $265. Yeah, right, like consumers are going to spend more than what the product costs to find out what the standard means. What the hell good are any of these standards when they are quoted by manufacturers but the consumers have to no way to know what they are? And you wonder why consumers don't know this stuff. -- __________________________________________________ __________ ** Share with others. Post replies in the newsgroup. ** If present, remove all "-nix" from my email address. __________________________________________________ __________ "w_tom" wrote in message ... Common mode surge does not become differential once inside house. It does not because voltage difference remains between wire with surge and earth ground. That common mode surge inside the building is still seeking earth ground, destructively, via appliances. However common mode surges can induce differential mode transients. Those long wires bundled with other wires will induce transients onto those other wires. This is the induced surge - not from electromagnetic fields of a distant CG strike. A plug-in protector tries to earth the common mode surge down safety ground wire. But that long ground wire, bundled with other wires, only induces the transient on those other wires. Just another reason why plug-in protectors are not effective as noted by last paragraph in: http://www.explan.co.uk/antisurge/modes.shtml Zerosurge and its competition Brickwall and Surgex are series mode protectors. Basically just low pass filters. They cannot work like a dam. Surges will simply overwhelm the dam. But they do work well as dikes. Difference: a dam must stop the flow whereas a dike only diverts the flow downstream. For series mode protectors to work, the surge must have a downstream path to earth ground. Series mode protectors will enhance the protection AND should also reduce noise on that circuit. But, they still require the surge to be provided a path to earth ground - and that is what shunt mode protectors do. Shunt mode protectors make a connection to earth ground only during the surge. Second reason why series mode protector require that shunt mode earth ground: the safety ground wire completely bypasses the filter. If surge is not earthed at service entrance, then surge will get to electronics by safety ground wire, unimpeded, right through series mode protector. They forget to mention that part in the Zerosurge summary. Even series mode protectors have this requirement - a surge protector is only as effective as its earth ground. MOVs do wear out with use. They are useless for small, daily transients such as spikes from a turned off switch. But then those spikes are so trivial as to only be called noise. So small that MOVs don't even see the transients. If those daily spikes caused damage, then the homeowner was replacing dimmer switches daily. For audio recording equipment, a series mode protector would keep those noise spikes away from recording equipment. But that noise from switches and motors does not damage electronics. If noise did damage, then we were all replacing clock radios every day - long before the PC even existed. MOV life expectancy is determined by joules. Since most plug-in protectors do not even claim to provide effective protection, they are also undersized - too few joules. As joules increase, the life expectancy of a surge protector increases exponentially. For example if a 345 joule protector (only using as little as 115 joules in protection) were to survive three same size, standard, 8/20 usec surges, then the 1000 joule 'whole house' protector would withstand on the order of 400 same sized transients. Numbers that plug-in manufacturers would rather avoid. Since lightning surges occur typically once every eight years, then a properly sized 'whole house' protector using MOVs will last more than long enough. They just forget to apply numbers when hyping MOV fear in that Zerosurge discussion. If using a 'whole house' protector, then any surge, interior or exterior, is earthed before it can create damage. Nothing inside the house should create a common mode surge. But even if something does, the 'whole house' protector still shunts the common mode transient to earth. Some papers will outrightly confuse. For example, 80% of transients can come from internal sources. IOW a 5 volt noise spike can be generated by an electric motor. If paper is written by an English major, then that 5 volts suddenly transpires into a 500 volt surge! In reality, if anything is creating destructive surges inside a house, then the homeowner is replacing dimmer switches, clock radios, and GFCI (RCD) daily. Appliances only create noise - well below what every household appliance must withstand. Surges come from exterior events. But too many authors on surges have eyes that glaze over as soon as numbers are provided. These people see surge everywhere - which is what plug-in manufacturers live off - misinformation. But lets assume that central air conditioner is generating surges. OK. The surge will immediately take out internal controls, furnace controls, and the house electronic thermostat. But if the air conditioner is creating this surge, then the surge protector must be at the air conditioner - not on everything else inside the building. And since central air is a dedicated circuit, then the 'whole house' protector would eliminate that mythical surge. Air conditioners and other household appliances don't create surges. They create noise - which hypsters of plug-in protectors forget to mention since they don't provide (or learn) numbers. Want to see an example of outright lies because the author probably did not understand fundamental concepts and probably feared numbers? http://www.howstuffworks.com/surge-protector.htm Facts so perverted as to be one long chain of lies. Many who promote surge protector don't even have basic electrical knowledge such as this author. Important for the surge protector to be at the service entrance for exterior common mode surge since those are higher frequency events. That high frequency in lightning generated surges are why the connection to earth ground must be less than 3 meters. At higher frequencies, wire length takes on a whole different characteristic. It is why a line - neutral protector is effective when the connection of line to neutral to earth ground rod is less than 3 meters (and other electrical characteristics such as not inside metallic conduit, no sharp bends, etc). Wire length is critical to where a surge protector is even connected to earth ground. Earth ground too far away all but does not exist - because of electrical characteristics of destructive surges. Your MOV on phone line is why MOVs are no longer used for such protectors. Semiconductors have long since replaced those MOVs. They either work, or become short circuits that tell human to replace them. MOVs have too much capacitance for use on phone lines. However some pathetic plug-in protectors do use MOVs for phone line protection. Your current phone line protector should be semiconductor based as has been standard for about 15 years. And it should be each phone wire, through protector, less than 3 meters to single point ground. Wire to wire protector do comparatively little. LED to indicate a surge protector as good is really nonsense. That LED can report one mode of failure, but cannot report the protector as good. This example from Zerosurge demonstrates the problem. They even removed all MOVs and the indicator light still declared the protector as OK: http://www.zerosurge.com/HTML/movs.html Transients on internal safety ground wires are irrelevant - basically don't exist - if the 'whole house' protector is installed on every incoming utility (or that utility is directly earthed before entering the building). If using internal plug-in protectors, then transients would be induced every where on safety grounds. Described above were induced surges. But then ground loops would use nearby appliances as a path to earth ground because breaker box earth ground is too far away. This is why an adjacent plug-in protector on AC input to a computer can contribute to damage of a modem - even if computer is powered off. That is correct. Adjacent plug-in surge protector completes a circuit to earth ground, destructively via modern. And modems, especially in North America, are most often damaged by AC electric surges. Once a surge has gotten inside the building, then it will find numerous destructive paths. No plug-in protector is going to stop that. In fact plug-in protectors can give that surge more potentially destructive paths to earth ground - such as the above modem example. Can MOVs create a fire? That is what UL1449 2nd Edition is about. Don't know of any ISO equivalent. But then if those 'adjacent to appliance' MOVs were effective, then MOVs are already inside the appliance. Appliances already have effective internal protection. Protection that assumes the 'big' transient - the surge - will be earthed before it can enter the building. Internal protection that makes adjacent plug-in protectors redundant. Internal protection that makes any other appliance generated 'noise' (not surge) irrelevant. Do you need an electrician? Even if plug-in protectors are installed, the electrician would still be necessary to upgrade a house ground. Many homeowners can install these 'whole house' protectors themselves - since it is that easy - and therefore sold in Home Dept. Even plug-in protectors require earth grounds. Older homes are too often missing this connection that is also essential to human safety. In North America, earth ground should be upgraded to, minimally, post 1990 NEC code requirements. Equivalent earthing is necessary throughout the world. That AC electric earth ground must be less than 10 feet from main disconnect (where neutral meets earth ground) and that earth ground (sometimes called GEC). And all other incoming utilities must also connect to that same earth ground. Exampled was a ground loop problem of computer at 1000 volts and printer at 400 volts. These problems are created when single point grounds are not used. Single point grounds that are necessary and provided by 'whole house' protectors. Resulting voltage difference is called ground loops. It is why peripherals connected to a computer should share same receptacle outlet if not same circuit (or ring). These transient voltages occur when the surge is not first earthed at the service entrance. These voltages are not generated by internal equipment. If any household device generates such voltages, then either a surge protector must be permanently connected to that appliance (the absurd solution) or the device must be removed as a threat to human safety. But then that device would remove itself; would self destruct anyway. Devices have more than sufficient internal protection even on interconnected ports IF the major surges are earthed before entering the building. Every incoming utility must either make a direct connection to single point earth ground OR make that connection via a 'whole house' protector. Plug-in protectors only provide surges with more destructive paths to earth ground such as via appliances. Plug-in protectors sell by forgetting to mention critical earthing OR provide any useful numbers. Plug-in protectors want you to not even discuss common mode transients because they are not selling effective protection. They do not even claim to provide common mode surge protection. One fact always remains - a surge protector is only as effective as its earth ground. No way around that fact. Vanguard wrote: As regards for *my* personal checklist that says to get a UPS with a sine wave output, yes, it is unnecessary if all you run from that UPS is your computer. I know the computer power supply will handle stepped wave output. Probably the printer, monitor, scanner, speakers, and modem, too. But eventually you upgrade your system and want a bigger UPS. In my case, I want a quieter one; the 2kVA unit that I have now has a fan that makes anywhere from 35 to 50 dB of noise. Will I toss it because I want one without a fan? No. Will I toss it when the batteries go bad? No, because they are replaceable; I've already replaced them once after 5-1/2 years of use (although I decided to use a bus bar instead of a heavy wire lead) at a cost of $140 for the 2 of them which was a tenth of buying a new unit. Since I'll use it for something else, like my audio/video gear, having a sine wave output is important. It gives me more choices on how to use the UPS other than just with computer gear. And for those of you that like pictures with the explanation: http://www.explan.co.uk/antisurge/modes.shtml But apparently it also depends on which country you live and their wiring standards: http://www.zerosurge.com/HTML/mode2.html http://www.zerosurge.com/HTML/works.html http://www.zerosurge.com/HTML/versus.html In the U.S., the neutral is bonded to earth ground at the service entrance, the only way to have common mode surges is from something inside your house, not from outside. Wouldn't a common mode surge coming at you from outside become a normal mode surge (since it then proceeds only on the [hot] line)? I think all the surge arrestors that I've seen here are mode 1 only (line-to-neutral) because neutral was tied to local ground (earth) at the service entry. No, I don't work for ZeroSurge and didn't know about their products until this thread had me hunting around on surge protection and methods. Their article at http://www.zerosurge.com/HTML/about.html had me grinning because I remember calling the telephone company to report problems. Three times they came out and did their local ring test. No problems. The fourth time, after looking around myself, I stood there while they tested. No problems again using both their test gear and making test calls. Took them to the basement and pointed at the MOV (metal oxide varistor) used across their lines. Replaced it, problem fixed. The problems I experienced were indicative of a high resistance short and I figured the MOV went bad. The MOV has very high resistance (10^9 ohms) at low voltages and passes very little current, but it has very low resistance at high voltages which shunts the surge but only for short-duration impulses. That's why they are rated in Joules (N joules = N amps across 1 ohm for *1 second*). MOVs can burn out with one good surge. Most surge protectors rely on MOVs but these eventually go bad over time after being repeatedly stressed. Several grains of zinc oxide (each with an individual breakdown of 3 volts) are sintered together to make a MOV. Each transient destroys some of those grains which reduces it's level of protection. The more it has protected you, the less it will protect you. The eventual failure is a short circuit (which is why sometimes they'll blow apart) and why a fuse should be used. If not fused, you'll smell when a MOV eventually shorts; it will smell like an electrical fire. If MOVs are not themselves fused or enclosed in a fire retardant, they can start fires (see http://www.smarthome.com/4401.html for a news report). Get a surge protector that has an LED for status to tell if the MOV is still good. The MOV should be [thermally] fuse protected or uses disconnect circuitry to shutoff the surge protector. That surge protector becomes nothing more than an extension cord when (not if) the MOV goes bad. A surge arrestor at the mains that goes bad is worthless, too. I can see how an LED can indicate if a TMOV is still good (http://snurl.com/2824), presuming the thermal element fries before the MOV has overly degraded. I suppose for a MOV you could do a similar setup in using a fuse and tie the LED between them. I've seen users employ surge protectors and UPS'es to protect the computer and forget about the telephone line to their modem or the cable going to their cable modem, especially if an internal modem, or even to their expensive audio gear. Also, to those that extol installing a whole-home surge arrestor (which may incur the expense of an electrician and requires it be your house to toy with), a whole-home surge arrestor is a point-of-entry device suppressing surges stemming from outside sources (utility company problems, transformer switching, etc.) but it won't do anything to suppress the high number of power surges that originate *inside* your house (appliances, projector bulb burnout, motors, air conditioning, etc.). I just saw some white papers regarding the origin of surges but had a problem in IE, had to close a window, and lost all of them. My recollection was that 20% of surges come from outside and 80% come from inside. Your A/C causing a surge is not usually a problem for your computer's power supply, but that huge lathe in an industrial environment is. While I can see the arguments for using a point-of-entry or service-entry surge arrestor for the whole home (if that is really an option for you, like you own that house), that may not eliminate surges generated within the home so I still see value for point-of-use surge protectors. w_tom extols dumping the surge to ground but neglects that data lines and audio equipment use this as their reference so the surges that are getting pummeled into local common can cause data and audio problems. It's a 20-year old spec based on using stand-alone devices and shunting the surges. Surge voltage on the ground wire varies by its length. With all the interconnected devices in computer systems, and if you tie in your audio/video system, too, you will have ground loops. If the surge induced on the safety ground at one computer is 1000V but it is 600V at another computer or printer, the 400V difference can cause disruption, degradation, or damage. Even small surges pumped into the safety ground wire can cause data errors, lockups, or other "weird" problems. |
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Welcome to deregulation where we don't want the government
to do standards. As a result, simple standards cost big bucks. UL1449 defines testing a surge protector so that it does not kill humans. Surge protector can fail during some of these tests and still pass because the only requirement is that protector not threaten human life. Transistor safety is irrelevant to UL1449 - or the principles on which all UL standards are created. Underwriter's Laboratory is about protecting human life. It does not care whether the product does as advertised. Some will cite ANSI/IEEE C62.1 standards. These are waveforms to simulate surge transients. C62.1 also does not mean the surge protector does anything. How does a waveform standard provide surge protection? But again, anything to sell a plug-in protector. They will hype C62.1 so that the naive feels this is an effective protector. Too much junk science reasoning only because a numerical standard is printed. One should first learn what that standard says. Most do not when they recommend a surge protector. A common mode transient inside a building seeks earth ground. It can seek earth via one or all wires. This being different from a differential mode transient that requires two wires. An AC power line transients will be earthed by the neutral, but other AC wires will continue into the building. However if the 'whole house' protector earths those other wires, then common mode surge become irrelevant. However all incoming wires must have some connection to earth for common mode transient protection. Earth has resistance. But more important, wire also has impedance. Now some numbers. Read multiple times if necessary since those numbers put surge protection into perspective and expose junk science myths. For example, a 20 amp copper wire of 18 meters may appear as 0.2 ohms resistance, but may also appear as 130 ohms impedance to a surge transient. This wire *impedance* is why a surge protector must make a less than 3 meter connection to earth. For example, lets say a 100 amp surge arrives at computer and adjacent plug-in surge protector. Surge protector attempts to shunt (divert, connect) that transient to earth ground via safety ground wire. But that would be 100 amps times 130 ohms or 13,000 volts. Computer and adjacent surge protector at something less than 13,000 volts relative to earth! IOW the surge will find other, destructive paths to earth such as through modem via phone line. This is typical modem damage - surge entering on AC mains and leaving to ground on phone line (UK has a different variation). Surge arrived on AC hot (black or brown) wire. Adjacent surge protector shunted surge to green safety ground wire. Surge protector, being too close to transistor and too far from earth ground, has contributed to surge damage. Modem often being a victim because it makes a good conductive path to earth ground. Now lets say same 100 amp surge encounters a 'whole house' protector with a 3 meter earth ground connection. That would be maybe 4 ohms impedance (and something less than 0.01 ohms resistance). IOW surge voltage from hot wire to earth ground is only 400 volts. Voltage at service entrance so low that 1000 and 2000 volt protection abilities built into appliances are not overwhelmed. Furthermore, that 18 meter wire between breaker box and appliance NOW becomes part of the surge protection solution rather than part of the problem. Impedance in those 18 meters makes it that much more difficult to find earth ground via the appliance - because surge was earthed by a 'whole house' protector. Of course that earth ground rod may not be the best earthing connection. No matter how big that earth ground, we can never get an excellent earth ground. Therefore better built homes, before the foundation is laid, install an Ufer ground with footings or a halo ground around the entire building. This makes earth beneath the building equipotential but for cost of copper wire. Very effective earthing at so little cost. However that copper wire loop can never be a perfect conductor; wire has impedance. So we want central earth ground to be a single point connection and the best earthing in the facility. Of course we can never make a perfect and best conductive single point ground..... Concepts of single point earthing are similar to why Hi-Fi components require single point grounding to eliminate hum and why A/D converters in so many electronics have a single point ground between the analog and digital circuits AT the A/D converter. Single point ground is a concept that requires understanding electronic circuit theory and electrical principles. These factors combine to make surge damage completely avoidable. Earthing for no surge damage is so easy if installed when the building is first built. Even so, we can install an effective earth ground, in most cases, by superior single point grounding techniques just at the service entrance. It may not be fully effective against the 200,000 amp direct strike. But then most people never confront this rare surge in their lifetime. My experience demonstrates earthing a direct strike with only 1 three meter ground rod. Damage to unprotected circuits was to everything. Damage on the protected circuits - nothing. Nothing except the utility meter that was partially damaged and failed later when the surge was earthed through meter. But this installation was more typical of a best protected facilities. This one facility has a less than 1 meter connection to a single earth ground rod in conductive soil. That distance to earth ground determines how much or little of a surge will seek earth ground inside the building. As noted previously, once inside the building, a surge will find too many destructive paths as even demonstrated by an IEEE paper. Concepts of surge protection were demonstrated in most papers of the 8 Nov 1998 issue of IEEE Transactions on Electromagnetic Compatibility. For example, one was a Norwegian maritime station installed to withstand the EMP of nuclear war. But so poorly earthed as to be damaged by a direct lightning strike. Authors demonstrated how earthing need be repaired. Legendary application notes are provide by the benchmark in surge protection - Polyphaser: http://www.polyphaser.com/ppc_pen_home.asp Does Polyphaser hype their product line? Of course not. Polyphaser earns their profits on providing real surge protection. Most who recommend surge protectors have never even heard of Polyphaser - which exposes how little they really knew. Polyphaser discusses earthing - extensively. Earthing so critical that one product has no earth ground connection. Instead the protector mounts directly on earth ground - because distance to earth - 0 meters - is that critical. Polyphaser even demonstrates how a direct strike to buried cable some distance from the building results in transistor failure - because incoming wire was not properly earthed to a single point bulkhead: http://www.polyphaser.com/datasheets/PTD1028.pdf Lightning strikes somewhere across the street close to the below grade West cable vault. ... The first line of defense is the telco protection panel, but the panel must be connected to a low resistance / inductance ground. There was no adequate ground available in the telephone room. Also note that serious surge protectors have little or no warranty. Polyphaser offers no warranty which is but another characteristic of better products. Concepts of earthing for surge protection demonstrated in this figure from an industry professional. Note that even buried wires can source an incoming transient. Both structures have their own central earth ground. All wires connect to that earth ground before entering structure - either by direct wire connection or via a surge protector: http://www.erico.com/erico_public/pd...es/Tncr002.pdf Other concepts: http://lists.contesting.com/_towerta...st/032935.html http://lists.contesting.com/_towerta...il/004413.html http://www.psihq.com/iread/ufergrnd.htm http://scott-inc.com/html/ufer.htm http://www.psihq.com/iread/strpgrnd.htm http://www.xantrex.com/support/docserve.asp?id=337 http://www.cinergy.com/surge/ttip08.htm http://www.ipclp.com/html/aud_ho_faq.html http://www.telebyteusa.com/primer/ch6.htm (see section 6.4) http://www.citelprotection.com/citel/tech_article.htm None of this is mentioned or implied by plug-in protectors because they are not selling effective surge protection. They are selling a product that is grossly overpriced (especially considering how few joules are installed), that avoids all mention of common mode transients, and that costs on the order of 10 to 50 times more per protected appliance compared to 'whole house' protectors. Where do most computer 'experts' get their education on surge protection? From boxes on retail shelves. Electrical concepts necessary to understand effective protection are not taught to nor understood by too many computer experts. For example, one need not even understand how to use a 3.5 digit multimeter to get A-plus Certified - to be a certified computer repairman. Insufficient electrical knowledge is why so few understand a concept well proven and demonstrated repeatedly since the 1930s - surge protection. Surge protectors are not surge protection. Surge protection is earth ground. A surge protector is only effective when it makes a connection to earth ground - as those so many professional comments repeatedly demonstrate. The most important point that no plug-in protector will ever mention - a surge protector is only as effective as its earth ground. Vanguard wrote: I'm not an electrical engineer but find this topic interesting. Could you please define what you mean by a "common mode" surge. I thought that meant the impulse was on both wires (line and neutral) and that a surge only on 1 wire was a "normal mode" surge. There are probably more technical explanations of common mode signals but the one at http://www.explan.co.uk/antisurge/modes.shtml seems to suffice (if you neglect the resistance to ground which apparently you do in claiming that slamming the surges to ground does not affect data transmission which uses ground as the reference). Say I have a common mode surge headed at my house (same impulse on both wires). At the service entry, the neutral is grounded to earth. Are you saying the impulse on the neutral still continues into the house? Then what was the point of grounding the neutral wire at the service entrance? And wouldn't this disqualify all your arguments regarding shunting the surge to ground if the shunt that already and permanently exists where the neutral wire is bonded to ground at the service entry doesn't work to eliminate the surge? Why would I expect a surge arrestor to do any better than a solid heavy gauge wire in shunting the surge to ground? If the surge is grounded on the neutral wire and doesn't proceed further and only the surge on the [hot] line gets through, why would that still be considered a common mode surge if the [companion] surge is now missing on the neutral wire? Also, do you know of any online links to ANSI, IEEE, and UL specifications (that I don't have to pay for)? As I mentioned, this is not my career but an interest as a result of my career and hobbies (i.e., it's not what I do but it can affect what I do). When I have gone hunting for the specs, it seems I end up as some site that wants me to pay for the documentation. For example, I want to find out about UL1449 referenced by a product, I go to http://www.ul.com and click the link for "Standards", and I get redirected to somewhere else (http://snurl.com/28fb) where I can buy a copy of the standard for $265. Yeah, right, like consumers are going to spend more than what the product costs to find out what the standard means. What the hell good are any of these standards when they are quoted by manufacturers but the consumers have to no way to know what they are? And you wonder why consumers don't know this stuff. |
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You probably hate being teacher as apparently I'm one of those dumb
students that just doesn't get it. If you want to get off the "hook" here, any free online resources that I can check that will support your statements? I see you provided some links and I will get to those later. You mentioned that MOVs are no longer used but neglected to mentioned the "other" solution. A zener diode maybe? Or a pair of high-current diodes oriented with opposite polarity with a zener in one leg of a diode to limit the voltage across the lines, like at http://snurl.com/28kb. Or an overvoltage-triggered SCR? Come on, whet our appetite and then leave it dangling. I'd sure love to know what's better than MOVs. I don't like the behavior of MOVs with them degrading from each use, shorting, and possibly causing a fire hazard. I haven't the time or budget to purchase a whole bunch of surge protectors, UPS'es, or power supplies to see what might be used instead. While this "other" solution would eliminate the degradation problem of MOVs (of eventually shorting and of catastrophic incendiary sacrifice), the characteristic fall-over to allow a large current to flow above the threshold voltage still applies (and still has to be a transient to prevent too much heat buildup, especially if semiconductors are involved). Yet you see articles like http://snurl.com/28ke where varistors are hailed as a better and faster acting solution (for crowbar or shunt solutions versus series solutions like ZeroSurge proposes that hopes it can choke the crap out of the transient). Gee, I thought we were moving away from MOVs. One should first learn what that standard says. That's my point. You claim that consumers are dumb. There's a good reason for this. They cannot get the information! If they have to pay membership dues and/or the costs to get a copy of the standard then they might as well as pay some "professional" to do all that for them. Instead of spending $50 to buy the product, the consumer would have to pay way over $500 just to get the info to which the product claims it conforms - and they still haven't bought the product yet! Great idea. Make standards but hide them from consumers. Consumers are NOT going to pay to get the information to which a manufacturer professes to conform so all that gobblety gook printed on the product is WORTHLESS! Yeah, if it is a product that is sold to consumers that are within the same industry then it makes sense to publish the standards conformity list on the product. I doubt that the majority of sales for whole-home surge arrestors, UPS'es, surge protectors, computers, printers, and the like are to same-industry insiders. A manufacturer of surge arrestors/protectors doesn't sell their product to another manufacturer of surge arrestors/protectors. Nothing on store shelves (retail or online) is geared for purchase only by 4-year degreed electrical engineers. If you sell something to someone outside your specialty, you should provide some decent information to those non-industry consumers. A common mode transient inside a building seeks earth ground. So for a common mode transient to NOT seek ground means it seeks one of the other lines which means the other line(s) must not also carry the transient. The reason it seeks ground is that the other lines also carry the transient so the differential between them isn't any different than normal; an impulse of 3000V on line (hot) seeks only ground only because there is also an impulse of 3000V on neutral. That means a common mode transient has to be on both the line (hot) and neutral so that the impulse on either will seek ground instead the other line. But the neutral was grounded at the service entry so it can't have the impulse. I thought (but don't know where to check) in the U.S. that surge arrestors operate in mode 1 (line to neutral), not in mode 2 for L-G and/or N-G. A common mode transient inside a building seeks earth ground. It can seek earth via one or all wires. This being different from a differential mode transient that requires two wires. Lost me again. There has to be a potential difference for current to seek a path across that potential difference. If line (hot) is carrying a 3000V impulse, and neutral has been bound to ground, then the impulse on the line has a potential difference with both the neutral and ground since both are at ground and will seek to both neutral and ground. Since local common (ground) and neutral are bound to earth ground at the service entry, the only other "wires" is the line (hot). I'll grant that neutral and local common are then separated as they are routed within the building, but by your own admonition the common mode surges or "noise" generated within a house are of no concern. An AC power line transients will be earthed by the neutral, but other AC wires will continue into the building. Those "wires" then consist of just the line (hot). Since neutral and local common were bound to earth ground at the service entry, what other "wires" would carry the transient into the building other than the [hot] line? I would think that one line (hot) that had the impulse whereas the other wires (neutral and ground) were earthed do not have the impulse would be a transverse or normal mode impulse. Earth has resistance. But more important, wire also has impedance. ... Okay, I understand about the impedance. That same impedance back to earth along the neutral line (since the surge protector should only do mode 1 crowbarring according to, I think, some 1996-year spec that I can't read regarding transient suppression) for that 13 kV impulse shunted at the MOV, or whatever other "solution", would be the same impedance would be the same impedance for the impulse to travel along the hot line from the service entry to the point of the crowbar. However, for sake of argument, we can say the impulse at the service entrance was 26 kV and got reduced to 13kV at the point of the shunt from hot to neutral. So the hot and neutral both have the same 13kV impulse and now have a differential of 0V because of the successful shunt. So there's no problem for the equipment protected past the shunt; i.e., the "upstream" equipment got saved. Surge protector attempts to shunt (divert, connect) that transient to earth ground via safety ground wire. No, mode 1 surge protection shunts to neutral, not [safety] ground. Surge protectors that do all-mode (L-N, L-G, N-G) are dangerous since shunting to safety ground defeats the *safety* of the ground. Someone touching the metal case which is attached to ground when the impulse got shunted from hot to ground and who also happened to be touching a pipe or other heavy conduit to earth would "feel the surge." And since there is a sizable albeit short-lived current. It's not like a static shock that has almost no current and where you simply jerk from the shock. Shunting to safety ground poses a health hazard. You don't put "protectors" in a home that can kill people, which, as you say, is the purpose of the UL standards to protect life and limb, and property survival is secondary. I think that was also part of the 1996-year transient standard (that I cannot check on) where only mode 1 is allowed. You do, however, now have 2 lines (hot and neutral) that have a 13 kV potential difference to the safety ground as opposed to the 1 line (hot) that you had before. IOW ? the surge will find other, destructive paths to earth such as through modem via phone line. Yeah, for the equipment that is not on the output side of the surge protector (i.e., upstream of the shunt). The shunt protects upstream equipment, not downstream equipment. You can buy surge protectors with more than enough outlets in which to plug all your computer equipment; if not, you can add powerstrips upstream of the surge protector. If you use 2 different surge protectors, one for your computer gear and another for your audio/video equipment, and despite them being plugged into the same wall outlet, the effective impulse at the shunt in each surge protector can be different by several hundred volts (due to the impedance from the length of the wires from the shunt in one surge protector to the shunt in the other surge protector). So obviously you don't want to have a connection running from your sound card to your stereo or from your video card's TV out to your television when these systems are on different surge protectors. Those interconnections are okay if you get a surge protector with more outlets so all of that equipment is on the same surge protector, or use a powerstrip upstream of the surge protector to put all your computer and audio/video gear on the same surge protector so they are all past the shunt for that surge. If you have modems getting fried, my bet is that the large A/C-D/C converter on the end of the power cord for the modem (which is the power supply) was too big for the surge protector's outlets or covered up too many other outlets so the user plugged it into the wall or into another power strip (surge protected or not) that was plugged into the wall. One side of the modem was connected to the protected computer system which doesn't experience the surge. The other side of the modem does experience the surge. You protected one side of the modem but not the other. Same goes for the telephone line input to the modem. You need to use a surge protector that incorporates a port for the telephone line so the surge from the telephone line also gets shunted before it reaches the modem AND without getting fed back to the computer (to then surge the RS-232 or PCI slot side of the modem). Surge protectors that simply shunt across the telephone line separately of the shunting for the power lines are no different than using 2 different surge protectors to protect 2 groups of separated equipment and then interconnecting that equipment across the 2 surge protectors as in the computer to A/V scenario. You don't go stringing surge capacitors from every wall outlet to protect that upstream equipment and then interconnect the upstream equipment across the surge protectors. Well, I suppose consumers probably do because the surge protectors probably didn't tell them not to, but then they also spewed a bunch of standards on the printed label on their product without the consumers having a means of deciphering what all that gibberish means. 'whole house' protector I wholeheartedly agree with you (or maybe it's "I vehemently agree with you" in this case) that a whole-home surge arrestor is the best solution - if it is an option to you. If you own the property, you probably are not restricted from altering that property. If you rent the house, you can't change the wiring even to add safety equipment without permission. If you are in an apartment, you usually have access only to the circuit breaker panel and that's it, and you are not permitted to even change anything there. If you can do it (to make the change) and if can do it (to install the whole-home surge arrestor), I'd say go for it right now. If you can't do the install yourself but are willing to pay an electrician then plan your budget to get that done as soon as possible. But if you canNOT do it (because it's not your property) then you have to find other solutions. One is to use surge protectors - but never interconnect the upstream equipment attached to separate surge protectors, and never connect some of the gear to the surge protector but leave part of it connected downstream of the surge protector, like the modem's honking big A/C-D/C converter or its telephone line. If you use multiple surge protectors, make sure it floats on the upstream side of that surge protector without ever connecting to anything attached on a different surge protector. You argue what is best. I'm arguing what is doable. If best is doable, do that. If best is not doable, do something lesser but still do it. Concepts of single point earthing are similar to why Hi-Fi components require single point grounding to eliminate hum and why A/D converters in so many electronics have a single point ground between the analog and digital circuits AT the A/D converter. Or why you end up using an isolation transformer to break the ground loop between preamp or low-level inputs and amplifier. Or why you use a 1-to-1 isolation transformer around a ferite core to isolate an antenna input on a receiver with its ground from the distanced ground for the antenna amplifier. Single point ground is a concept that requires understanding electronic circuit theory and electrical principles. I don't doubt it. But the non-industry public never really gets much education on educational television. And apparently trying to get at the standards set by those industries is overly improbable to the consumers that use those products produced by those industries. The industry isn't very forthcoming with detailed information regarding their products, either. Ever try to get the actual diagrams for a surge protector, UPS, or even a power supply? Even if they don't have any patented circuits or gizmos, they still hide what *is* their product. And if it's patented then it's patented and they should still be able to tell you. A lot of fear. But then a lot of thiefs, too. Thanks for all the links. I'll go visit them and see what else I can learn or, at least, get an opinion to see if it can be verified by another. (The http://www.polyphaser.com/datasheets/PTD1028.pdf link didn't work so I'll have to hunt around on that site for it.) Also note that serious surge protectors have little or no warranty. Well, the warranties [extended to connected equipment] are often there but the real burden is proving that the damage was caused by a surge that got past their equipment, and then usually having to re-prove it to a judge. With a vendor of a graphic card, the cost of supplying a replacement is very minor. But having to settle on a $25K to $50K claim on a warranty means you end up in court, or if you settle out of court then, as with all such settlements, you waive your right to divulge any information regarding the settlement (i.e., if they pay, you have to shut up about the whole mess). Polyphaser offers no warranty which is but another characteristic of better products. Doesn't matter, however, since Uniform Commercial Codes and state warranty laws will enforce intent of purpose. You sell a surge protector then that's what you are selling and it better had do its job, but the only coverage for loss in that case is only for the product and nothing connected to it. Warranties only provide coverage in addition to what the law requires, and whether stated or not they will recognize that "laws in your area may apply which affect coverage and enforcement of this warranty and/or other implied warranties" or something along that line. Just because you don't provide a warranty doesn't mean there isn't one. That's the first time someone has claimed that the *lack* of a warranty equates to *greater* quality. "We sell it. We don't stand behind anything we sell." "Everything is ... AS-IS." "We make promises about what it will do. We're good at making promises. We don't promise to honor those promises." I think what you meant to say is that Polyphaser only warranties its own products and nothing that is connected to it or anything generated from that connected equipment. They don't provide a "lure" to bait consumers, a lure that almost instantly disintegrates when you try to exercise that warranty. But that's no big surprise. Microsoft Excel's warranty only warranties the software and the only recourse you have is to get your money back for the cost of its purchase, not for all the data it screwed up. Very few warranties ever cover anything other than the product itself without regard to whatever else the failure of the product might have affected. Thanks for all the info. More meat to chew on. |
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MOVs are not used on phone lines - too much capacitance.
Semiconductor based devices are used; replacing a MOV like device often called the carbons: http://www.inwap.com/inwap/chez/Phoneline.jpg Another is called Sidactor. Avalanche diodes (Transzorb, Transil) are sometimes used as low power replacements for MOVs. But conventional avalanche diodes also have too much capacitance for phones. Therefore specialized version is used. For conventional power protection, there is no better 'buy' than MOVs. If worried about degradation or fire, then MOVs are insufficient and undersized - as found in some power strips. Fire is no longer a problem if the surge protector is UL1449 certified AND located where fire is not a danger such as the service entrance. But where does a plug-in surge protector end up? Under papers on a desk or on floor behind furniture in a deep shag carpet or in a pile of dust balls. UL1449 says they should not create sparks or fire, but is that where you want an undersized protector? As stated previously, series mode surge protectors such as Zerosurge, et al still require the earthing provided by shunt mode protectors. Complete facts not provided in that Zerosurge discussion of MOVs forget to mention that MOVs are some of the best surge protectors. That fire and degradation problem only exists when a myth purveyor forgets to provide numbers - promotes using junk science. Plug-in protector does have those problems when undersized. What good is providing facts? Toothpaste did nothing until Crest provided Fluoride. Listerene still does nothing. And yet so many will promote and buy Listerene and Scope as demonstrated by the large shelf space in supermarkets. Why don't they provide the numbers? Because profits are too great to be fully honest about mouthwash - and how it does nothing effective. Consumers often buy on feel and on advertisement that promotes half facts. Or STP oil treatment. Or Oxyclean detergent. Needed are more Consumer Reports. Problem is that once a person had accepted something as fact (believes the propaganda without much doubting), then he holds all contrarian information to a higher threshold of acceptance. He outrightly doubts anything contrary to that original propaganda. For example, the public thinks the blackout was a result of insufficient capacity. Nonsense. The grid was not fully loaded - had sufficient capacity - when the blackout happened. NERC and DOE state that capacity is not a problem - now or in the projected future. Problem is control. The grid does not have a facility shortage. It has a serious control problem directly traceable to how some company management (ie FirstEnergy) operate. But since early pundits said the grid is too old, too overloaded, and not built to do what it is now doing, then the public only hears and believes that propaganda. Propaganda - not the facts published before the blackout by NERC and DOE - are what the public hears. This same mindset is also why plug-in surge protectors are sold. People are quick to only believe what they first heard - even though scientific facts - the truth - takes longer to be discovered, presented, and explained. However information printed on a surge protector is not gobblety gook. Missing facts demonstrate that plug-in protectors are not effective. They will claim differential mode protection. But they don't claim common mode protection. They don't even discuss critical earthing. However a public that believes a surge protector will stop, block, or absorb a surge cannot be bothered with the new discovery - missing information. Computer power supplies are also sold using the same deception. All power supplies can be shorted and not damaged. Supply can fail (regulator outputs excessive voltage) and nothing inside a computer must experience that excessive voltage (overvoltage protection). If the computer attempts to draw too much power, then a power supply is not damaged (overpower protection). However so many buy supplies without ever looking for specifications. Therefore $20 power supply (that also create radio interference) are sold widely - because the computer assembler never learned basic electricity and makes no attempt to do so. The information is in specifications - most often in the missing parts of that specification. That $20 supply never provides specifications because it does not provide essential power supply functions. So many ineffective plug-in surge protectors don't even provide those specifications - and that, unfortunately, is acceptable to any consumers. The junk scientist says his computer works today, therefore a power supply is not defective. But a power supply missing those essential functions really is defective - regardless of whether the computer works today. How all technologies work. Welcome to a problem in America - too many business degrees and too little education on how things work. Too many feel that don't need to see the bigger picture because computer works today. Myopia of business school graduates as even W E Deming repeatedly noted. Fundamental to understanding how things work: it must work both experimentally and theoretically - else it does not work. That concept is taught in high school science. And yet still people will deny their education - using junk science reasoning instead, such as a big buck warranty, to believe facts not in existence. Because the power supply works now, then it is not defective? Because Shuttle launched in freezing weather previously, then it will always launch in freezing weather without exploding? That was the reasoning. Junk science reasoning is widespread. Differential mode transient - two wires where transient only seeks that second wire as a return path - nothing else. Common mode - one or many wires where the transient can seek any path to earth ground. All surge protectors install MOVs L-N, L-G, and N-G - what was described in last post as dangerous. Shunting to safety ground poses a health hazard. You don't put "protectors" in a home that can kill people... But that is how plug-in protector are wired. And that short transient is not considered dangerous to people according to UL standards. Person must first be part of a complete circuit. Incoming on grounded appliance, but where is the outgoing path? Destructive to appliance but not necessarily dangerous to human. Again, wire impedance means that plug-in protector will not shunt a common mode surge only back to breaker box. It will shunt that surge also destructively in other directions through appliance - and yes, maybe through a person. (But only if that person has a different good connection to earth ground.) Also if the surge was differential mode, then the surge would never seek those other, destructive paths. Common mode surge: cut neutral and ground wire; and the common mode surge will still seek earth ground only down the remaining hot wire. Surge continues unaffected. Cut that neutral and ground wire; the differential mode surge current cannot exist. I don't understand your 13K (and 26K which does not exist) example. But assumed that transient is a voltage source. Current source is why impedance on black wire (coming to appliance) is irrelevant AND why series mode protectors are not effective without corresponding shunt mode protection. Volt will increase, as necessary, to overwhelm any impedance on the black wire AND created by low pass filter in a series mode protector. Because the transients is current mode, then a transient must be earthed before it can enter the building. Else voltage will increase, as necessary, to overwhelm series mode protector or galvanic (isolation transformer) protector, or internal appliance protection. Furthermore a plug-in protector does try to shunt the surge on safety ground. Yes it may also shunt on neutral, but plug-in protector are not effective because they do shunt surges on safety ground - a distance too far from earth ground. Modem damage. Does not matter whether modem was internal or external. Common mode transient from AC mains found earth ground, destructively, via modem. Lets assume plug-in surge protector is connected to same outlet that an another electronic appliance takes power. Some think the appliance is not protected if not plugged into the power strip. Wrong. The appliance in outlet gets same shunt protection as if plugged into power strip. If power strip surge protector stops or blocks surges, then an appliance would need be plugged into the power strip. But that is not what shunt mode surge protectors (ie power strip protectors) do. They shunt meaning that everything around them - before and after the power strip - have equivalent protection. Lets say you don't own the property - cannot get landlord to install a 'whole house' protector. Best one can do is locate an outlet closest to breaker box (on same phase) and plug the largest joule plug-in protector into that outlet. Best place for that plug-in protector may be outlet on breaker box - the closest connection to earth ground. To install a plug-in protector as if it was a 'whole house' protector. This assumes the building has some earth ground. Many, even built in 1970, are missing that essential (and once provided) safety ground. No earth ground means no surge protector will be effective. Pragmatism - good luck getting a landlord to upgrade his earthing system since so many say, "Lights work just fine" and will not spend money. As demonstrated by the previous power supply and Shuttle examples, the landlord is denying failure exists. To complicate issues, those three light outlet testers will report a defective ground. But that does not test earth ground. It is only a safety ground check. Some actually have posted that an outlet checker will verify earth ground AND that earth ground is tested by a ground indicator light on some power strips. Those tests will detect a failed safety ground, but will not report a good safety ground, and make no claims for earth ground. Actually, the best solution to surge protection would be to have it required on all homes - as is required on phone lines. First a halo ground or Ufer ground would be installed when home is built. Or the concrete basement floor using the reinforcement wire mesh as part of the earthing system - to make earth beneath a building equipotential. The 'whole house' protector would be installed by same electrical code rules that solved electric fire problems. Then we have an earthing system that even solves surge problems created by geological variations AND we have a surge protector that is already properly connected. Currently we must customize every surge protector installation because we don't install earth ground and surge protectors in a standard installation. Customizing makes the 'how' part complex. This need for surge protectors is quite recent - only with the 1970 appearance of transistors in all homes. However we still build new homes as if the transistor did not exist. A standard installation including superior earthing and surge protector would provide almost universal protection at very low cost. Presently, some homes need massive earthing (that was not as expensive when the house was being built) to solve future surge damage. All surge damage is that avoidable and unnecessary. Vanguard wrote: You probably hate being teacher as apparently I'm one of those dumb students that just doesn't get it. If you want to get off the "hook" here, any free online resources that I can check that will support your statements? I see you provided some links and I will get to those later. You mentioned that MOVs are no longer used but neglected to mentioned the "other" solution. A zener diode maybe? Or a pair of high-current diodes oriented with opposite polarity with a zener in one leg of a diode to limit the voltage across the lines, like at http://snurl.com/28kb. Or an overvoltage-triggered SCR? Come on, whet our appetite and then leave it dangling. I'd sure love to know what's better than MOVs. I don't like the behavior of MOVs with them degrading from each use, shorting, and possibly causing a fire hazard. I haven't the time or budget to purchase a whole bunch of surge protectors, UPS'es, or power supplies to see what might be used instead. While this "other" solution would eliminate the degradation problem of MOVs (of eventually shorting and of catastrophic incendiary sacrifice), the characteristic fall-over to allow a large current to flow above the threshold voltage still applies (and still has to be a transient to prevent too much heat buildup, especially if semiconductors are involved). Yet you see articles like http://snurl.com/28ke where varistors are hailed as a better and faster acting solution (for crowbar or shunt solutions versus series solutions like ZeroSurge proposes that hopes it can choke the crap out of the transient). Gee, I thought we were moving away from MOVs. One should first learn what that standard says. That's my point. You claim that consumers are dumb. There's a good reason for this. They cannot get the information! If they have to pay membership dues and/or the costs to get a copy of the standard then they might as well as pay some "professional" to do all that for them. Instead of spending $50 to buy the product, the consumer would have to pay way over $500 just to get the info to which the product claims it conforms - and they still haven't bought the product yet! Great idea. Make standards but hide them from consumers. Consumers are NOT going to pay to get the information to which a manufacturer professes to conform so all that gobblety gook printed on the product is WORTHLESS! Yeah, if it is a product that is sold to consumers that are within the same industry then it makes sense to publish the standards conformity list on the product. I doubt that the majority of sales for whole-home surge arrestors, UPS'es, surge protectors, computers, printers, and the like are to same-industry insiders. A manufacturer of surge arrestors/protectors doesn't sell their product to another manufacturer of surge arrestors/protectors. Nothing on store shelves (retail or online) is geared for purchase only by 4-year degreed electrical engineers. If you sell something to someone outside your specialty, you should provide some decent information to those non-industry consumers. A common mode transient inside a building seeks earth ground. So for a common mode transient to NOT seek ground means it seeks one of the other lines which means the other line(s) must not also carry the transient. The reason it seeks ground is that the other lines also carry the transient so the differential between them isn't any different than normal; an impulse of 3000V on line (hot) seeks only ground only because there is also an impulse of 3000V on neutral. That means a common mode transient has to be on both the line (hot) and neutral so that the impulse on either will seek ground instead the other line. But the neutral was grounded at the service entry so it can't have the impulse. I thought (but don't know where to check) in the U.S. that surge arrestors operate in mode 1 (line to neutral), not in mode 2 for L-G and/or N-G. A common mode transient inside a building seeks earth ground. It can seek earth via one or all wires. This being different from a differential mode transient that requires two wires. Lost me again. There has to be a potential difference for current to seek a path across that potential difference. If line (hot) is carrying a 3000V impulse, and neutral has been bound to ground, then the impulse on the line has a potential difference with both the neutral and ground since both are at ground and will seek to both neutral and ground. Since local common (ground) and neutral are bound to earth ground at the service entry, the only other "wires" is the line (hot). I'll grant that neutral and local common are then separated as they are routed within the building, but by your own admonition the common mode surges or "noise" generated within a house are of no concern. An AC power line transients will be earthed by the neutral, but other AC wires will continue into the building. Those "wires" then consist of just the line (hot). Since neutral and local common were bound to earth ground at the service entry, what other "wires" would carry the transient into the building other than the [hot] line? I would think that one line (hot) that had the impulse whereas the other wires (neutral and ground) were earthed do not have the impulse would be a transverse or normal mode impulse. Earth has resistance. But more important, wire also has impedance. ... Okay, I understand about the impedance. That same impedance back to earth along the neutral line (since the surge protector should only do mode 1 crowbarring according to, I think, some 1996-year spec that I can't read regarding transient suppression) for that 13 kV impulse shunted at the MOV, or whatever other "solution", would be the same impedance would be the same impedance for the impulse to travel along the hot line from the service entry to the point of the crowbar. However, for sake of argument, we can say the impulse at the service entrance was 26 kV and got reduced to 13kV at the point of the shunt from hot to neutral. So the hot and neutral both have the same 13kV impulse and now have a differential of 0V because of the successful shunt. So there's no problem for the equipment protected past the shunt; i.e., the "upstream" equipment got saved. Surge protector attempts to shunt (divert, connect) that transient to earth ground via safety ground wire. No, mode 1 surge protection shunts to neutral, not [safety] ground. Surge protectors that do all-mode (L-N, L-G, N-G) are dangerous since shunting to safety ground defeats the *safety* of the ground. Someone touching the metal case which is attached to ground when the impulse got shunted from hot to ground and who also happened to be touching a pipe or other heavy conduit to earth would "feel the surge." And since there is a sizable albeit short-lived current. It's not like a static shock that has almost no current and where you simply jerk from the shock. Shunting to safety ground poses a health hazard. You don't put "protectors" in a home that can kill people, which, as you say, is the purpose of the UL standards to protect life and limb, and property survival is secondary. I think that was also part of the 1996-year transient standard (that I cannot check on) where only mode 1 is allowed. You do, however, now have 2 lines (hot and neutral) that have a 13 kV potential difference to the safety ground as opposed to the 1 line (hot) that you had before. IOW ? the surge will find other, destructive paths to earth such as through modem via phone line. Yeah, for the equipment that is not on the output side of the surge protector (i.e., upstream of the shunt). The shunt protects upstream equipment, not downstream equipment. You can buy surge protectors with more than enough outlets in which to plug all your computer equipment; if not, you can add powerstrips upstream of the surge protector. If you use 2 different surge protectors, one for your computer gear and another for your audio/video equipment, and despite them being plugged into the same wall outlet, the effective impulse at the shunt in each surge protector can be different by several hundred volts (due to the impedance from the length of the wires from the shunt in one surge protector to the shunt in the other surge protector). So obviously you don't want to have a connection running from your sound card to your stereo or from your video card's TV out to your television when these systems are on different surge protectors. Those interconnections are okay if you get a surge protector with more outlets so all of that equipment is on the same surge protector, or use a powerstrip upstream of the surge protector to put all your computer and audio/video gear on the same surge protector so they are all past the shunt for that surge. If you have modems getting fried, my bet is that the large A/C-D/C converter on the end of the power cord for the modem (which is the power supply) was too big for the surge protector's outlets or covered up too many other outlets so the user plugged it into the wall or into another power strip (surge protected or not) that was plugged into the wall. One side of the modem was connected to the protected computer system which doesn't experience the surge. The other side of the modem does experience the surge. You protected one side of the modem but not the other. Same goes for the telephone line input to the modem. You need to use a surge protector that incorporates a port for the telephone line so the surge from the telephone line also gets shunted before it reaches the modem AND without getting fed back to the computer (to then surge the RS-232 or PCI slot side of the modem). Surge protectors that simply shunt across the telephone line separately of the shunting for the power lines are no different than using 2 different surge protectors to protect 2 groups of separated equipment and then interconnecting that equipment across the 2 surge protectors as in the computer to A/V scenario. You don't go stringing surge capacitors from every wall outlet to protect that upstream equipment and then interconnect the upstream equipment across the surge protectors. Well, I suppose consumers probably do because the surge protectors probably didn't tell them not to, but then they also spewed a bunch of standards on the printed label on their product without the consumers having a means of deciphering what all that gibberish means. 'whole house' protector I wholeheartedly agree with you (or maybe it's "I vehemently agree with you" in this case) that a whole-home surge arrestor is the best solution - if it is an option to you. If you own the property, you probably are not restricted from altering that property. If you rent the house, you can't change the wiring even to add safety equipment without permission. If you are in an apartment, you usually have access only to the circuit breaker panel and that's it, and you are not permitted to even change anything there. If you can do it (to make the change) and if can do it (to install the whole-home surge arrestor), I'd say go for it right now. If you can't do the install yourself but are willing to pay an electrician then plan your budget to get that done as soon as possible. But if you canNOT do it (because it's not your property) then you have to find other solutions. One is to use surge protectors - but never interconnect the upstream equipment attached to separate surge protectors, and never connect some of the gear to the surge protector but leave part of it connected downstream of the surge protector, like the modem's honking big A/C-D/C converter or its telephone line. If you use multiple surge protectors, make sure it floats on the upstream side of that surge protector without ever connecting to anything attached on a different surge protector. You argue what is best. I'm arguing what is doable. If best is doable, do that. If best is not doable, do something lesser but still do it. Concepts of single point earthing are similar to why Hi-Fi components require single point grounding to eliminate hum and why A/D converters in so many electronics have a single point ground between the analog and digital circuits AT the A/D converter. Or why you end up using an isolation transformer to break the ground loop between preamp or low-level inputs and amplifier. Or why you use a 1-to-1 isolation transformer around a ferite core to isolate an antenna input on a receiver with its ground from the distanced ground for the antenna amplifier. Single point ground is a concept that requires understanding electronic circuit theory and electrical principles. I don't doubt it. But the non-industry public never really gets much education on educational television. And apparently trying to get at the standards set by those industries is overly improbable to the consumers that use those products produced by those industries. The industry isn't very forthcoming with detailed information regarding their products, either. Ever try to get the actual diagrams for a surge protector, UPS, or even a power supply? Even if they don't have any patented circuits or gizmos, they still hide what *is* their product. And if it's patented then it's patented and they should still be able to tell you. A lot of fear. But then a lot of thiefs, too. Thanks for all the links. I'll go visit them and see what else I can learn or, at least, get an opinion to see if it can be verified by another. (The http://www.polyphaser.com/datasheets/PTD1028.pdf link didn't work so I'll have to hunt around on that site for it.) Also note that serious surge protectors have little or no warranty. Well, the warranties [extended to connected equipment] are often there but the real burden is proving that the damage was caused by a surge that got past their equipment, and then usually having to re-prove it to a judge. With a vendor of a graphic card, the cost of supplying a replacement is very minor. But having to settle on a $25K to $50K claim on a warranty means you end up in court, or if you settle out of court then, as with all such settlements, you waive your right to divulge any information regarding the settlement (i.e., if they pay, you have to shut up about the whole mess). Polyphaser offers no warranty which is but another characteristic of better products. Doesn't matter, however, since Uniform Commercial Codes and state warranty laws will enforce intent of purpose. You sell a surge protector then that's what you are selling and it better had do its job, but the only coverage for loss in that case is only for the product and nothing connected to it. Warranties only provide coverage in addition to what the law requires, and whether stated or not they will recognize that "laws in your area may apply which affect coverage and enforcement of this warranty and/or other implied warranties" or something along that line. Just because you don't provide a warranty doesn't mean there isn't one. That's the first time someone has claimed that the *lack* of a warranty equates to *greater* quality. "We sell it. We don't stand behind anything we sell." "Everything is ... AS-IS." "We make promises about what it will do. We're good at making promises. We don't promise to honor those promises." I think what you meant to say is that Polyphaser only warranties its own products and nothing that is connected to it or anything generated from that connected equipment. They don't provide a "lure" to bait consumers, a lure that almost instantly disintegrates when you try to exercise that warranty. But that's no big surprise. Microsoft Excel's warranty only warranties the software and the only recourse you have is to get your money back for the cost of its purchase, not for all the data it screwed up. Very few warranties ever cover anything other than the product itself without regard to whatever else the failure of the product might have affected. Thanks for all the info. More meat to chew on. |
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Looking back on your original list of damaged components, I
notice PSU was damaged. What type of PSU was this? What / where are specifications for this PSU? David LeBrun wrote: Ok...I am not disputing the science behind all this...I couldn't even begin to... My intent when I started this thread was to get people's experiences with power related death to components because I was simply curious why the cpu, memory and video card (items which I would expect to go first) survived when other components (which I thought were more durable) failed. I agree with you 100% that a UPS protects data as they have saved my stuff on numerous occasions. ... |
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Not sure...but I'm told it was a cheap one...and was replaced with an
Enermax 300W I don't know if the PSU was replaced before the rest of the damage occured or if it all happened at the same time. I have been following along with the discussion but most of what you and Vanguard have been exchanging is beyond me. Dave. "w_tom" wrote in message ... Looking back on your original list of damaged components, I notice PSU was damaged. What type of PSU was this? What / where are specifications for this PSU? David LeBrun wrote: Ok...I am not disputing the science behind all this...I couldn't even begin to... My intent when I started this thread was to get people's experiences with power related death to components because I was simply curious why the cpu, memory and video card (items which I would expect to go first) survived when other components (which I thought were more durable) failed. I agree with you 100% that a UPS protects data as they have saved my stuff on numerous occasions. ... |
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Here is the reason I asked about supply. Was there a power
surge or was a power surge just assumed? Original power supply was cheap - often missing essential overvoltage protector circuits. If this inferior power supply suffered regulator failure, then power supply outputs excessive and destructive voltages. In a standard power supply such as the Enermax, overvoltage protector circuits would have shorted out that overvoltage. Other components inside the system would not have been damaged because overvoltage was shorted out by protector circuit - that is often missing in cheap power supplies. Maybe there was no power surge. Damage was simply created by a human who did not know to get a supply with essential functions such as that overvoltage protector. IOW supply was purchased only on price; not using specifications. Therefore the supply failed and took out that long list of computer components. Many of the damaged components are typical of a power supply sold with a good price and no specifications. Only component not damaged that I would have expected damage to was RAM. Power supply would destroy disk drives but not CPU. IOW that above entire discussion may have been irrelevant because system was not damaged by a surge. System was damaged by human who did not know how to buy a power supply. Such defective supplies are widespread; even sold in CompUSA. David LeBrun wrote: Not sure...but I'm told it was a cheap one...and was replaced with an Enermax 300W I don't know if the PSU was replaced before the rest of the damage occured or if it all happened at the same time. I have been following along with the discussion but most of what you and Vanguard have been exchanging is beyond me. Dave. "w_tom" wrote in message ... Looking back on your original list of damaged components, I notice PSU was damaged. What type of PSU was this? What / where are specifications for this PSU? |
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Howdy there, a good thread. I have used Enermax power supplies in the
past and have been very pleased with them. I also have an Antec power supply that came with an Antec case I recieved. Both power supply units have been excellent. From my experience, you get what you pay for. If you want a good quality component, I suggest you purchase products accordingly ! There are other excellent manufacturers of power supply units out there as well. Just be careful what you buy. I suggest you leave it to those who have had many year experience to give advice on which manufacturers have good reputations and courteous service with their products. Shall the best come out of your endeavor. |
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