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Salty_Peaks
@as54203.net

Salty_Peaks to garys_2k

Anon

to garys_2k

Re: [Electrical] Whole House Surge Protector Lost All Its Magic Smoke

Thanks 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?
Salty_Peaks

Salty_Peaks

Anon

iOS is horrible; desolder

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

garys_2k to Salty_Peaks

Premium Member

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.

cowboyro
Premium Member
join:2000-10-11
CT

cowboyro

Premium Member

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.

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

garys_2k

Premium Member

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.

rfhar
The World Sport, Played In Every Country
Premium Member
join:2001-03-26
Buicktown,Mi

rfhar

Premium Member

Most MOV failures I have heard about had a hole in the side when they failed

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

garys_2k

Premium Member

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.
LittleBill
join:2013-05-24

LittleBill to cowboyro

Member

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

cowboyro
Premium Member
join:2000-10-11
CT

cowboyro

Premium Member

Breakers should trip within one AC cycle (16ms) on currents 10x higher than the rating.
LittleBill
join:2013-05-24

LittleBill

Member

from my understanding, generally there is very little current and very high voltage

cowboyro
Premium Member
join:2000-10-11
CT

1 edit

cowboyro

Premium Member

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.
TheMG
Premium Member
join:2007-09-04
Canada
MikroTik RB450G
Cisco DPC3008
Cisco SPA112

1 recommendation

TheMG

Premium Member

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!
lutful
... of ideas
Premium Member
join:2005-06-16
Ottawa, ON

lutful

Premium Member

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.