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Salty_Peaks to garys_2k
Anon
2014-Apr-15 10:27 pm
to garys_2k
Re: [Electrical] Whole House Surge Protector Lost All Its Magic SmokeThanks everyone for the replies and teaching -- seems these systems provide a low impedence ground when the MOVs go bye bye. Did the PCB cut traces or deaolder die to current? I asssume they shunt to ground and depending on the level of line/mains failure would trip the main breaker? |
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Salty_Peaks |
Salty_Peaks
Anon
2014-Apr-15 10:28 pm
iOS is horrible; desolder |
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garys_2k Premium Member join:2004-05-07 Farmington, MI |
to Salty_Peaks
said by Salty_Peaks : I asssume they shunt to ground and depending on the level of line/mains failure would trip the main breaker? It's installed on its own dedicated two pole breaker so the main shouldn't ever trip. I don't know if the breaker feeding this one had tripped, but I assume it was. That much carbon would present pretty easy leakage from pole to pole. |
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cowboyro
Premium Member
2014-Apr-16 11:40 am
said by garys_2k:It's installed on its own dedicated two pole breaker so the main shouldn't ever trip. Then it's pretty much useless. You want the main breaker to trip - and fast - in order to quickly stop the high voltage from hitting the house circuit when the MOVs fail open half a second later. |
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garys_2k Premium Member join:2004-05-07 Farmington, MI |
garys_2k
Premium Member
2014-Apr-16 12:11 pm
I think these MOVs failed closed, that'd be the only way the breaker would trip. Failing open wouldn't trip the breaker, the surge is likely long gone by the time the breaker would trip. |
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rfharThe World Sport, Played In Every Country Premium Member join:2001-03-26 Buicktown,Mi |
rfhar
Premium Member
2014-Apr-16 12:27 pm
Most MOV failures I have heard about had a hole in the side when they failed |
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garys_2k Premium Member join:2004-05-07 Farmington, MI |
garys_2k
Premium Member
2014-Apr-16 12:29 pm
Yeah, I'll see if I can pull it open, wash off all the carbon and see where it actually failed. It may have been a circuit board trace for all I can see. |
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to cowboyro
said by cowboyro:said by garys_2k:It's installed on its own dedicated two pole breaker so the main shouldn't ever trip. Then it's pretty much useless. You want the main breaker to trip - and fast - in order to quickly stop the high voltage from hitting the house circuit when the MOVs fail open half a second later. this will never happen, breakers will never trip fast enough to stop a surge, not even sure if fast acting fuses could do it |
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cowboyro
Premium Member
2014-Apr-16 1:46 pm
Breakers should trip within one AC cycle (16ms) on currents 10x higher than the rating. |
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from my understanding, generally there is very little current and very high voltage |
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cowboyro
Premium Member
2014-Apr-16 2:17 pm
said by LittleBill:from my understanding, generally there is very little current and very high voltage The current is dictated by the voltage. 2000A should trip a 200A breaker "instantly". The cheap protectors definitely won't do that though... some solid varistors or a crowbar type of device will fare much better, but won't cost $0.50 to manufacture. |
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TheMG Premium Member join:2007-09-04 Canada MikroTik RB450G Cisco DPC3008 Cisco SPA112
1 recommendation |
TheMG
Premium Member
2014-Apr-16 9:18 pm
said by cowboyro:said by LittleBill:from my understanding, generally there is very little current and very high voltage The current is dictated by the voltage. 2000A should trip a 200A breaker "instantly". The cheap protectors definitely won't do that though... some solid varistors or a crowbar type of device will fare much better, but won't cost $0.50 to manufacture. Thing is... transient surges are typically of a very short duration, lasting only a very small fraction of an AC cycle. The mechanical inertia/lag of the components in the breaker is enough that a breaker will not typically trip in response to a rapid transient, even though that transient may cause hundreds or thousands of amps to flow for a very short time. Neither will a fuse, because the fuse element has a thermal mass and the rapid transient will not be of sufficient duration to actually heat it to fusing temperature. There's no such thing as "instant" in the real world, just "very fast". A crowbar type surge suppressor would be very undesirable. In some situations, surge events can be an almost daily occurrence. Would be a very major nuisance! |
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lutful... of ideas Premium Member join:2005-06-16 Ottawa, ON |
lutful
Premium Member
2014-Apr-16 10:56 pm
Thyristor TVS devices have the fastest respnse time but can handle fewer joules and lower voltages than MOVs.
The absolute best lightning surge protection: MOVs with spark-gap bypass to ground at the utility side (like the earlier schematic) and then Thyristor TVSs between lines/neutral and neutral/ground on the home side. It is used widely to protect cellular and radio/TV broadcasting equipment.
But I don't know if any whole-house brand/model implements that architecture. |
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