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Discussion Starter · #1 ·
I run a seismic research station in S Korea with the Air Force, we have a site that has had chronic power problems, every rainstorm for several weeks we would need to drive out and reset the input power breaker. The last few times the other techs noticed arching damage in the box but could not determine if it was new or historical. Most of the power at these sites is old some as old a 10 years. The last time I reset the breaker there was a very obvious arc and the breaker was locked out for later replacement. I went back out with a new breaker box with Square D 20A GFCI breakers (all we had on stock) replaced the old box with the new box and all was well, until the next storm. At this point every time there is a storm that breaker pops. The power is run from a transformer down in two phase AC one leg is plugged into the box, the output is to a ALPHA brand UPS, output of that is to a VICORE brand 110VAC to 24VDC converter then to the 24VDC input of our equipment.
Any Ideas are appreciated
 

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DGR,IABD
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It would seem obvious to me (without looking at it) that there is water getting into some piece of equipment or it's associated connections during the rain, tripping the breaker. Remember, it only takes 6 milliamps to trip a GFCI breaker, which ain't much. If any of this equipment is connected with underground wiring, some of this may even be failing.

It would take a "Megger" check to pin down the source of the fault more exactly. You need to get ahold of the electrical engineer or the electician for your site and have them do a megger check of the branch circuit wiring to find the fault. This problem should be quite easy to find with a megger.
 

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Start the paperwork for the engineers now and it might get done before you are rotated. LOL
 

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I do have one question; what does seismic research have to do with the Air Force?

As I was writing that, I don't think that I want to know the answer.
 

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Discussion Starter · #6 ·
There in enters the problem I AM (a poor excuse for) THE ENGINEER sob. What is a Megger? I am more than willing to admit rain may be getting into the system somewhere. My first course of action is to order a non GFCI breaker, if that doesn’t work I’m going to go find a corner to cry in.

As to the question what does seismic research have to do with the Air Force, we have a mandate to be able to detect nuclear explosions “in, on, and above the earth” and nukes make a recognizable “shake” when detonated underground so that’s what we do.
 

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DGR,IABD
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MakeItWork said:
What is a Megger?
A Megger, one tradename for a megaohm meter, is like an ohm meter that puts a high voltage across conductors. This will "jump the gap" across terminations that are just barely shorted out and only intermittantly causing troubles. You normally set the megaohm meter to twice operating voltage (500 volts, in your case) and disconnect the loads so that you don't fry them. Traditionally, meggers have a hand crank on the side to build the test voltage, but as of late they've been battery operated with digital displays. It's not exactly an instrument for a frustrated seismic station guy or a DIY'er to try using until you have a little bit of training on its use.
 

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Removing the GFCI?

MakeItWork said:
There in enters the problem I AM (a poor excuse for) THE ENGINEER sob. What is a Megger? I am more than willing to admit rain may be getting into the system somewhere. My first course of action is to order a non GFCI breaker, if that doesn’t work I’m going to go find a corner to cry in.
I would suggest your first course of action to check for ways that excessive moisture could be entering your enclosure. Seal off entering conduits, check gaskets AND ALSO change out your GFCI breaker not with a NON-GFCI breaker but *gasp* with another NEW GFCI breaker. The thing is either tripping for a good reason or it really has become faulty.
Removing the fault protection altogether only ignores the fault condition and that's not a good thing either.

If all still doesn't work, look into replacing the wires between the breaker and load. (The megger test will tell you if you have faulty wires, but by the time you do that, you could probably have them changed out.)
After that, if it is still tripping, uh oh, look at your load.

Good luck!
 
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