No. Why do you think it would? if the surge suppresser clips at a safe voltage to protect from spikes, it won't go any higher with a overvoltage condition, but the MOV or other protection device quickly overheats as it tries to maintain the proper voltage. If the line voltage is high enough, it will trip the Breaker, or blow the fuse for that AC circuit. The protective device can only dissipate a small amount of heat before it self destructs.
. Damage to a TV obviously depends on the TV and the overvoltage.
The IEEE guide goes on a length how the protected load can be connected across the MOVs or connected to the incoming line. If connected across the MOVs, the protected load will be disconnected when overheating MOVs are disconnected on failure. I suspect that MOVs will overheat and be disconnected before high current operates overcurrent devices. A few plug-in suppressors will disconnect on overvoltage. .
. The intended point was that MOVs don?t normally fail by "open[ing] back up". .
. MOVs, like anything else, will fail. The normal way they fail is low resistance .
. It isn?t a design. It is the way they work. .
. Why would you think UL isn?t testing for safety risks.
. A lot of houses have signal entrances too distant from power services. It is better to have a good "single point ground". But everything I have read indicates multiport plug-in suppressors with high ratings will provide protection for almost everything but a direct lightning strike to a house. The IEEE guide has an illustration of a multiport suppressor protecting when a cable entry is too far from the power service. The impedance to surges of the wiring inside the house greatly limits the current, and hence energy, available at a plug-in suppressor.
On Fri, 29 Feb 2008 02:23:56 -0500 Michael A. Terrell wrote: | snipped-for-privacy@ipal.net wrote: |> |> On Thu, 28 Feb 2008 01:45:12 -0600 bud-- wrote: |> |> | Martzloff has also written "In fact, the major cause of TVSS [surge |> | suppressor] failures is a temporary overvoltage, rather than an |> | unusually large surge." |> |> And these would not damage the TV? | | | No. Why do you think it would? if the surge suppresser clips at a | safe voltage to protect from spikes, it won't go any higher with a | overvoltage condition, but the MOV or other protection device quickly | overheats as it tries to maintain the proper voltage. If the line | voltage is high enough, it will trip the Breaker, or blow the fuse for | that AC circuit. The protective device can only dissipate a small | amount of heat before it self destructs.
This was a discussion about a suggestion tha the MOV condunction voltage should be higher than now used (330V for 120V systems). He wants to raise that voltage to avoid certain situations causing TVSS failure so the protection against spikes (above 800V) is maintained longer. My position is that the swells as high as 565V RMS could in fact cause damage to the TV. Under his proposal, these would be be suppressed. I think that is a bad idea because these voltage swells really can do damage.
On Fri, 29 Feb 2008 03:53:29 -0600 bud-- wrote: | snipped-for-privacy@ipal.net wrote: |> On Thu, 28 Feb 2008 01:45:12 -0600 bud-- wrote: |> |> | Martzloff has also written "In fact, the major cause of TVSS [surge |> | suppressor] failures is a temporary overvoltage, rather than an |> | unusually large surge." |> |> And these would not damage the TV? | . | Damage to a TV obviously depends on the TV and the overvoltage. | | The IEEE guide goes on a length how the protected load can be connected | across the MOVs or connected to the incoming line. If connected across | the MOVs, the protected load will be disconnected when overheating MOVs | are disconnected on failure. I suspect that MOVs will overheat and be | disconnected before high current operates overcurrent devices. | A few plug-in suppressors will disconnect on overvoltage.
And you are saying what?
|> |> If that voltage is what the UL says is right, and tests for (I presume |> |> they have surge simulation tests under power to verify that MOV devices |> |> don't just open back up under a surge event, etc) |> | . |> | UL1449 has quite a few tests. MOVs fail by conducting. |> |> Conducting when the voltage reaches the specified level is doing the job |> expected of them. | . | The intended point was that MOVs don?t normally fail by "open[ing] back up". | . |> I would not call that a failure. | . | MOVs, like anything else, will fail. The normal way they fail is low | resistance
In they sense they no longer provide protection, that is a failure.
|> The device may not |> be usable after that event (the MOV being fused to conduct), but that is |> part of the design. | . | It isn?t a design. It is the way they work.
The design of the surge protector is to use the characteristic of the MOVs.
|> I believe UL should be testing surge protectors with respect to things |> like whether they pose safety risks. Will it electrocute me when I flip |> the switch on it? Will it break and short out when I try to plug in to |> one of its outlets? Will the cord on it fail and expose wires when it is |> handled a little roughly? Will it develop a hot spot and result in my |> house burning down when I am away or asleep? Will it explode when given |> the design voltage plus or minus the prescribed margin range? | . | Why would you think UL isn?t testing for safety risks.
I didn't say they aren't. I'm commenting about the expectations as a response to a comment about what I thought were poor expectations.
On Fri, 29 Feb 2008 04:02:22 -0600 bud-- wrote: | snipped-for-privacy@ipal.net wrote: |> On Thu, 28 Feb 2008 12:11:16 -0600 bud-- wrote: |> |> |
Maybe almost. Definitely not all.
| to a house. The IEEE guide has an illustration of a multiport suppressor | protecting when a cable entry is too far from the power service. The | impedance to surges of the wiring inside the house greatly limits the | current, and hence energy, available at a plug-in suppressor.
Tell that (impedance of inside wiring) to some past devices I've had destroyed by lightning induced surges, or direct hits.
If you are talking about a direct lightning strike to a building, I specifically exclude them above. Protection includes lightning rods. If you have a tower antenna you are talking about a whole different level of protection.
If you are talking about general electronic "devices", the branch circuit impedance does not limit the voltage (although US panels and receptacles will arc over at about 6kV).
For plug-in suppressors, the suppressor clamps the voltage and the branch circuit impedance greatly limits the current.
. Surge suppressors are intended to protect against surges. Raising the clamp voltage is to lower unnecessary suppressor exposure to surges that do not damage connected equipment.
Surge suppressors are not intended to protect against longer duration swells or even longer duration overvoltage. Martzloff's comment above is that the major cause of failure is overvoltage, which suppressors are not intended to protect against.
If you keep the clamp voltage low, you are likely not increasing protection from swells because a swell may well kill the MOV anyway. To protect against overvoltage get a suppressor that disconnects on overvoltage.
But what you are doing in the discussion is force fitting the MOV TVSS into protecting against events that it was not designed for. It's like insisting that your umbrella protect against the rain in a hurricane. It might keep the rain off briefly, before the wind blows it apart.
Ed
On Sat, 01 Mar 2008 03:12:55 -0600 bud-- wrote: | snipped-for-privacy@ipal.net wrote: |> On Fri, 29 Feb 2008 02:23:56 -0500 Michael A. Terrell wrote: |> | snipped-for-privacy@ipal.net wrote: |> |> |> |> On Thu, 28 Feb 2008 01:45:12 -0600 bud-- wrote: |> |> |> |> | Martzloff has also written "In fact, the major cause of TVSS [surge |> |> | suppressor] failures is a temporary overvoltage, rather than an |> |> | unusually large surge." |> |> |> |> And these would not damage the TV? |> | |> | |> | No. Why do you think it would? if the surge suppresser clips at a |> | safe voltage to protect from spikes, it won't go any higher with a |> | overvoltage condition, but the MOV or other protection device quickly |> | overheats as it tries to maintain the proper voltage. If the line |> | voltage is high enough, it will trip the Breaker, or blow the fuse for |> | that AC circuit. The protective device can only dissipate a small |> | amount of heat before it self destructs. |> |> This was a discussion about a suggestion tha the MOV condunction voltage |> should be higher than now used (330V for 120V systems). He wants to |> raise that voltage to avoid certain situations causing TVSS failure so |> the protection against spikes (above 800V) is maintained longer. My |> position is that the swells as high as 565V RMS could in fact cause |> damage to the TV. Under his proposal, these would be be suppressed. |> I think that is a bad idea because these voltage swells really can do |> damage. | . | Surge suppressors are intended to protect against surges. Raising the | clamp voltage is to lower unnecessary suppressor exposure to surges that | do not damage connected equipment.
The last 7 words are the part we do not agree on.
| Surge suppressors are not intended to protect against longer duration | swells or even longer duration overvoltage. Martzloff's comment above is | that the major cause of failure is overvoltage, which suppressors are | not intended to protect against.
I've read discussions and online pages to the contrary. If you have put forth your theory ahead of time, I could have recorded the locations for you.
| If you keep the clamp voltage low, you are likely not increasing | protection from swells because a swell may well kill the MOV anyway. To | protect against overvoltage get a suppressor that disconnects on | overvoltage.
The surge suppressor already does this. Sure, it can _die_ while doing this. The MOV shorts across, causing an increase in current that trips the supplementary breaker in the strip (usually integrated in the switch). There, appliance protected by one low cost device.
Maybe what should have proposed was that we use a more expensive device that integrates higher level MOVs with overvoltage sensors. If he can show that such a MORE EXPENSIVE device is worth the extra cost in the longer term, he wins. But I think he cannot. The reason ons that even a doubling of cost to make such a device (I think it is more than just that) would not produce a win for the consumer because really too few surge protectors have this issue for the total payout to not be increated by the more expensive device.
On Sat, 01 Mar 2008 14:39:23 GMT ehsjr wrote: | snipped-for-privacy@ipal.net wrote: |> On Fri, 29 Feb 2008 02:23:56 -0500 Michael A. Terrell wrote: |> | snipped-for-privacy@ipal.net wrote: |> |> |> |> On Thu, 28 Feb 2008 01:45:12 -0600 bud-- wrote: |> |> |> |> | Martzloff has also written "In fact, the major cause of TVSS [surge |> |> | suppressor] failures is a temporary overvoltage, rather than an |> |> | unusually large surge." |> |> |> |> And these would not damage the TV? |> | |> | |> | No. Why do you think it would? if the surge suppresser clips at a |> | safe voltage to protect from spikes, it won't go any higher with a |> | overvoltage condition, but the MOV or other protection device quickly |> | overheats as it tries to maintain the proper voltage. If the line |> | voltage is high enough, it will trip the Breaker, or blow the fuse for |> | that AC circuit. The protective device can only dissipate a small |> | amount of heat before it self destructs. |> |> This was a discussion about a suggestion tha the MOV condunction voltage |> should be higher than now used (330V for 120V systems). He wants to |> raise that voltage to avoid certain situations causing TVSS failure so |> the protection against spikes (above 800V) is maintained longer. My |> position is that the swells as high as 565V RMS could in fact cause |> damage to the TV. Under his proposal, these would be be suppressed. |> I think that is a bad idea because these voltage swells really can do |> damage. |> | | But what you are doing in the discussion is force fitting | the MOV TVSS into protecting against events that it was not | designed for. It's like insisting that your umbrella | protect against the rain in a hurricane. It might keep | the rain off briefly, before the wind blows it apart.
That's a poor analogy.
The MOV based TVSS is most like to short circuit in a damaging event and cause the incoming breaker (the switch in the power strip, for example) to trip. The power strip might now be a usless hunk of metal and plastic, but the appliance to be protected is still protected for the duration.
|> Tell that (impedance of inside wiring) to some past devices I've had |> destroyed by lightning induced surges, or direct hits. |> | If you are talking about a direct lightning strike to a building, I | specifically exclude them above. Protection includes lightning rods. If | you have a tower antenna you are talking about a whole different level | of protection.
I was talking about either direct strike or an induced strike on any of the incoming service lines.
| If you are talking about general electronic "devices", the branch | circuit impedance does not limit the voltage (although US panels and | receptacles will arc over at about 6kV). | | For plug-in suppressors, the suppressor clamps the voltage and the | branch circuit impedance greatly limits the current.
... until the breaker can trip and open the circuit if the voltage is not as high as the arc-over level.
Ok, what specific TVSS models claim to be designed to do what you stated: protect against the overvoltage in the damaging event? Or are you just trolling?
Ed
Bud's own posts, including Page 42 Figure 8, say otherwise. Protectors without earth ground are not an effective solution to surges that seek earth ground.
When utilities do not enter at a common point, then a better solution is to make a lager single point ground by merging all electrodes with a buried wire. The title is "Preventing Damage Due to Ground Potential Difference". A utility demonstrates how to accomplish this in wrong, right, and preferred pictures:
Two reasons are why earthing provides protection. For even better protection, some loop a building with a buried ground wire - techniques such as halo or Ufer grounds. Effective protection is about conductivity and equipotential. That buried ground wire improves both making all appliances even better protected. Protection is only as effective as the earthing which is why high reliability facilities are obsessive about their earthing.
Lightning striking utility wires down the street may be a direct strike to appliances inside a building. We install protectors to make direct lightning strikes irrelevant. 'Whole house' protectors are sized and earthed so that direct lightning strikes do not find earth ground, destructively, via household appliances. This is how protection was implemented even 100 years ago.
Lightning view utility's AC electric wires as an antenna connected to household appliances. What was proven in radio stations also applies to protecting household appliances. Protection proven 100 years ago for radio station antennas and telephone company facilities is also provided by a properly earthed 'whole house' protector. Only plug-in protectors don't do what has been proven effective for over
100 years.Type of surge that typically overwhelms protection already inside all appliances is the direct lightning strike. We install a 'whole house' protector to make direct lightning strikes. Bud does not recommend plug-in protectors for the type of surge that typically does damage? What kind of protection is that? Profitable. Ineffective. Does not remain functional after a typically destructive surge. Appliances can be damaged by a direct lightning strike if lightning to AC utility wires is not earthed. We earth an effective protector for direct lightning strikes. We install plug-in protectors to maximized profits.
Discussion about effective protection is about making the direct lightning strike irrelevant - so that the protector even remains functional. 'Whole house' protectors earth direct lightning strikes AND remain functional. Bud admits that plug-in protectors do not do what is necessary for effective protection.
If you really want to protect your equipment you should have a very fast operating fuse, selected for ~125% of the FLA of your equipment in front of the MOV. Then while the MOV is self destructing the fuse will blow
On Sat, 01 Mar 2008 18:01:51 GMT ehsjr wrote: | snipped-for-privacy@ipal.net wrote: |> On Sat, 01 Mar 2008 14:39:23 GMT ehsjr wrote: |> | snipped-for-privacy@ipal.net wrote: |> |> On Fri, 29 Feb 2008 02:23:56 -0500 Michael A. Terrell wrote: |> |> | snipped-for-privacy@ipal.net wrote: |> |> |> |> |> |> On Thu, 28 Feb 2008 01:45:12 -0600 bud-- wrote: |> |> |> |> |> |> | Martzloff has also written "In fact, the major cause of TVSS [surge |> |> |> | suppressor] failures is a temporary overvoltage, rather than an |> |> |> | unusually large surge." |> |> |> |> |> |> And these would not damage the TV? |> |> | |> |> | |> |> | No. Why do you think it would? if the surge suppresser clips at a |> |> | safe voltage to protect from spikes, it won't go any higher with a |> |> | overvoltage condition, but the MOV or other protection device quickly |> |> | overheats as it tries to maintain the proper voltage. If the line |> |> | voltage is high enough, it will trip the Breaker, or blow the fuse for |> |> | that AC circuit. The protective device can only dissipate a small |> |> | amount of heat before it self destructs. |> |> |> |> This was a discussion about a suggestion tha the MOV condunction voltage |> |> should be higher than now used (330V for 120V systems). He wants to |> |> raise that voltage to avoid certain situations causing TVSS failure so |> |> the protection against spikes (above 800V) is maintained longer. My |> |> position is that the swells as high as 565V RMS could in fact cause |> |> damage to the TV. Under his proposal, these would be be suppressed. |> |> I think that is a bad idea because these voltage swells really can do |> |> damage. |> |> |> | |> | But what you are doing in the discussion is force fitting |> | the MOV TVSS into protecting against events that it was not |> | designed for. It's like insisting that your umbrella |> | protect against the rain in a hurricane. It might keep |> | the rain off briefly, before the wind blows it apart. |> |> That's a poor analogy. |> |> The MOV based TVSS is most like to short circuit in a damaging event and |> cause the incoming breaker (the switch in the power strip, for example) |> to trip. The power strip might now be a usless hunk of metal and plastic, |> but the appliance to be protected is still protected for the duration. |> | | Ok, what specific TVSS models claim to be designed to do | what you stated: protect against the overvoltage in the | damaging event? Or are you just trolling?
Apparently most all of them ... either designed that way or just happen to operate that way. Otherwise the previously mentioned paper would not have needed to be written.
I asked for specific models. Your answer does not contain a specific model. So you are trolling after all.
Ed
. You are disagreeing with Martzloff, who has done a lot of research on surge protection an has numerous published papers. The same immunity has also appeared elsewhere such as a PCMagazine review of plug-in suppressors. .
. Contrary - overvoltage is the major cause of failure? - you are again disagreeing with Martzloff.
Contrary - not intended to protect against swells and overvoltage? - provide a source that says plug-in suppressors are intended to protect against swells and overvoltage. Like maybe specs from few manufacturers that Ed asked for.
"Put forth your theory ahead of time" - apparently a new newsgroup requirement? .
. By the time current reached well over 15A required to trip a 15A breaker in a short time, the MOV would be toast. UL has required since 1998 that thermal disconnects be provided to disconnect overheating MOVs. Or fuses as Greg suggests, but selected by the manufacturer which can have operating characteristics closely matched to the MOVs, may also open. It is unlikely that protection would come from a breaker.
Repeating: "The IEEE guide goes on a length how the protected load can be connected across the MOVs or connected to the incoming line. If connected across the MOVs, the protected load will be disconnected when overheating MOVs are disconnected on failure." Similar comments are in the NIST guide.
Your response was "And you are saying what?"
What: that is the probable protection route indicated in both guides if a plug-in suppressor can provide protection from overvoltage. Both guides make clear not all plug-in suppressors are wired to disconnect the protected load with the MOVs. .
. Repeating: "To protect against overvoltage get a suppressor that disconnects on overvoltage." They disconnect the load and MOVs. .
. "He"? Is "he" Martzloff? I have never seen Martzloff indicate a MOV based surge suppressor should protect against swells or overvoltage.
The "IEEE Recommended Practice for Powering and Grounding Sensitive Electronic Equipment" (Emerald book) does not indicate plug-in suppressors are an effective means of protecting against swells or overvoltage.
Perhaps you could use a plug-in suppressor with overvoltage protection built in, as above.
If you want to use failure of MOVs to protect your equipment I would suggest a suppressor from a reputable manufacturer where the manufacturer says the suppressor will protect from swells and overvoltage. Given hype, I suggest using a device where the manufacturer also has a warrantee on protected equipment.
Saying plug-in suppressors should protect against swells and overvoltage they are not designed for does not make them effective.
======================== Or perhaps you could use a device the Emerald book indicates might be effective. For houses that would be a UPS. But make sure the manufacturer says the UPS will protect against swells and overvoltage.
. w_ apparently believes a strike to a utility line down the street with multiple paths to ground, a distant connection and coming through controlled entrance to a house is the same as a strike to an adjacent tower antenna sticking far above anything else and connected to sensitive electronics in the house. .
. UL listed suppressors have MOVs from H-G, N-G, H-N. That is all combinations and all possible surge modes. w_ has never explained how a common mode surge coming in on a power service gets past the N-G bond required at all US services. Past the service the surge is transverse mode. .
. ?Direct lightning strike? is ?direct strike to a building? in the beginning quote. Apparently w_ thinks that a service panel suppressor provides that protection, without lightning rods. w_ lives in a fantasy world. .
. I admit they do not protect against a ?direct lightning strike to a building?. What a radical idea.
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