I have a large breaker (1,600 amp, 600v) that is tripping intermitantly. This breaker has all of the usual electronic sensing. It's tripping every 18 - 140 hours. Power analyzer isn't picking up anything. Load is a constant 200 amps. I'm not sure if its the breaker or some type of ground fault. A replacement breaker is $10,000.
There is another panel nearby that I can use to temporarily re-feed the load with a smaller, spare, thermal magnetic breaker. The customer has some salvaged 4/4 type s/o cord on hand. To save them some money I'm thinking of using this to jumper over to the other panel approximately 20' away and see what happens. Both panels are in the same locked electrical room with access limited to qualified persons only.
Any thoughts on this? Also I'm thinking of using a separate 4/4 cord to feed each phase leg v.s. splitting them among all three cords i.e., all four wires in each cord will be connected in parallel to the same phase leg. Do you see any problems with doing this>

None at all .... especially with a truly temporary arrangement, to diagnose the problem.

Let's face it ... a $10K breaker is not something to casually replace. Perhaps you can send it to the manufacturer for testing? Dare I suggest .... it might even be possible to repair the thing, should it prove to not meet specs.

I'm sorry but I have to strongly disagree on this one, especially the way "temporary" can get to be a pretty long time. You wouldn't be doing a valid test because the substituted breaker wouldn't have the same sensing as the suspect breaker. I would check to see if they got an Amptector or other test unit when they got their switchgear. Get someone in to do the prescribed maintenance for the breaker. You can verify the long time, short time, instantaneous, and ground fault trip settings. Sometimes the switches on a trip unit getting exercised will end up fixing the problem. We switch between the different sensing circuits (A,B,C) for the different tests so we make sure we use each one at least once. In your case, I would go through each test, 3 times. If nothing else, note all the multiplier and delay settings, exercise the pots & switches, and put them back to where you found them.
Joe

How far is the nearest hospital with a burn unit?

Good your going to save money, you may need it for the long recovery period.

When someone has this type of switchgear, they should also have the ability to do proper maint and repairs, I my opinion proper testing is the only may, there are plenty of qualified testing companies out there.

Joe, I can't disagree with your approach ... whatever this "amptector" is!

Yes, "temporary" is very often abused. Helectric is describing a tightly controlled use, in a protected location. Using another breaker to verify that the problem is within a breaker, or in the circuit, is a valid procedure.

The problem is, nobody is going to tie up $10K just on a 'maybe.' He stated he has already tried monitoring the circuit, and has not found any transients. Does he continue looking at the circuit - or does he first eliminate the breaker from the list of possibilities.

That brings us to testing the breaker. My tool belt certainly has no means of testing a breaker ... that has been something left to the manufacturer. Even then, many of the tests are performed on a sampling basis, as the test itself destroys the breaker.

If this "amptector" is some sort of way to field test the breaker, and identify any problems with the breaker .... I think it's a great idea.

In the meantime, things need to be kept running. If the reliability of the breaker is itself the question, then I maintain that poses a greater hazard than the risk posed by the temporary bypass for trouble-shooting purposes.

Naturally, the dishonest use of 'temporary' makes this judgment invalid.

All of the customers equipment is periodically tested by a testing company. The cost to have someone travel here to test just one breaker would make up a significant portion of the cost to just replace it.
The cable will be protected by a breaker that is properly sized for both the cable and the load served so I don't see any problems with doing this. True, it will be a different style breaker with different sensing/trip characterstics and will not be a true test of the suspect breaker but if it holds then it will allow me to keep the customer's operation going while the original breaker is shipped, tested, and return shipped.

http://www.eaton.com/ecm/idcplg?Idc...on=Primary&&dDocName=TB01900002E

I'm sorry Reno. "Amptector" was just the name of an older trip unit. Page 10 of this pdf shows an example of a breaker tester that I use. You plug it into 120VAC and the front or side of a breaker. It is not destructive at all because you use it to send signals to the trip unit. You can't trust your trip settings unless you verify them with something like this. The procedure is a little confusing at first but with practice, you could probably get through all the tests in under 15 minutes.

He didn't tell us the particulars of the suspect breaker but the one he wanted to use for his test doesn't seem to have any ground fault sensing. My gut is telling me that a 200A constant load on 1600 AT breaker is most likely tripping out on ground fault. That's why a good first step is to log all the settings and exercise them. Then, try easing out on the GF settings if necessary. But still, settings should checked at least every couple of years to avoid nuisance trips or a breaker that won't trip when it should.
Joe

Joe, although I didn't mention it I have already excersized all of the settings and have been gradually increasing the GF setting. If the breaker is tripping due to ground fault then I would expect the power analyzer to show some increase in current at the time of trip. I'm not seeing this and I am using a very high end analyzer. The current is flat line to trip. This is a Square D breaker and it will likely become the fifth one of this type that I've replaced in the last three years. Two of these were 3,000 amp and cost $27,000 each. All behaved exactly as this one is acting now. All factory post mortems stated failure of the electronic trip portion of the breaker. They were all more cost effective to replace v.s. rebuild. All breakers are 10 years old and are in a clean, temperature comtrolled environment.

Thanks for the link, Joe. Might be a useful thing to have in a production environment ....

HE ... when you said 'electronic trip' and "Square D" together, I had this 'deja vu' feeling ... but, in my instance, it turned out to be a PoCo issue that was causing problems. Since you've been monitoring things, I'm sure that cause has been ruled out.

Given the history .... well, looks like the Sq D units have a definite lifespan. Again, considering the costs of the equipment ... I might start looking into another make of gear - while, at the same time, expressing your displeasure, with documentation, to Sq D. Amazing things just might happen ....

I'd wanted to just address the temporary connections. What is the available fault current? If it is high enough then the single cables are potential for broken arms and legs too. A big heavy cable can remove a head if the fault current is high enough the forces to move a big heavy cable can be substantial.
I suspect the problem is in the trip unit and that probably can be changed. Nevermind the potential hazard of open gear and Arc Faults

Having no experience with large Circuit Breakers, may I still introduce some ideas?

How do the trip modules receive power? Is it possible that the control power source is providing "dirty" power which results in failure of the trip modules?

Is the "clean, temperature comtrolled environment" the area where the switchgear is installed, not necessarilly the environment of the trip modules? If so, could the modules see significantly higher temperatures due to outside air being introduced thru unused conduits or floor penetrations?

Larry C

Good point, Mikesh ... I had forgotten how things can fly about during a major fault.

HE,
I'm a little bummed out at you for dribbling out the most critical info: A HISTORY OF FAILED TRIP UNITS IN THE SAME LINE-UP!!!! What's up with that? It's a ton of you-know- what that replacing the trip units should cost more than installing new breakers! Especially when one of their folks should be doing it, on site, with minimal cost to your customer. And did you press them for the exact failures in the trip units? A bad run of electrolytics? Tantalum caps in backwards? At the price you're paying, you deserve specifics! Did you happen to put your high-end analyzer on the breaker control power?

The more I think about this the more ticked off I get. You know that test isn't a real test, and that your trip unit is likely shot! You just want your customer up and running with a potentially deadly work-around. Do you think any peceived blessings from us would let you sleep any better at night if this situation broke badly? I'm sorry if I have you pegged wrong but I've been down this road before!
People leave out vital info to justify doing something that they already know they shouldn't!
Joe

Joe, I can assure you that I don’t come to this site for anyone’s blessings and I take full responsibility for any actions that I take regardless of where I get advice. I posted here because I respect the opinions of those that share this site. To me the synergy that’s created by their collective minds is truly a valued resource. I also appreciate the level of professionalism and mature tone that I typically find here as opposed to other forums. Since I was uncertain about how effectively I’ve been/am dealing with this I came here. My intent was to get any and all thoughts regarding this situation, nothing more.

OK, I'll take your word for it. Here is my opinion! That place should have at least one spare feeder breaker that is of a common amp frame and maximum amp trip used in your line-up. It could be racked in in place of a flaky breaker with the trip settings dialed down as appropriate for the substituted breaker.
Joe

Square D/Group Schneider has had a history of certain lines of electronic low voltage breakers (SE series etc.) failing and little factory support for repair. Their approach is to offer new at grossly inflated prices. The problem with these breakers is almost always the electronics. It certainly causes their customers to look at other manufacturers for future equipment upgrades. Part of the reason for this approach is that specifiers and purchasing agents look primarily at initial cost when buying for new installation or upgrade. Very little consideration is given to total lifetime cost and reliable factory support at a reasonable rate. All the manufacturers therefore respond to this business model in the same way-competitive initial pricing, inflated prices and no repair parts later.

Homer,

Based on my experiences with this I'd have to say that you're dead on. I also wonder if the manufacturers not openly taking responsibility for defective breakers is due to concerns about liability for the lost customer revenue that result from related production shutdowns. I know of a few contractors in this area that have landed on the wrong end of this type of law suit when their work has been suspected of causing similar losses. This is somewhat similar to a delay of progress claim in the construction world.

http://www.etc-12.com/trip-units/sqd-amptector-trip-unit.html

What about somebody else's trip unit? I'm not vouching for this company's product because I just found them via Google. If a company makes crap and won't stand behind it, they deserve to get retrofitted out of the market. If the mechanicals of your breakers are sound, seek out another trip unit. Better yet, ask your Square D rep who's aftermarket trip unit he or she reccommends. Maybe you'll get better treatment.
Joe

Larry,

Regarding your question about where the retrofit trip modules receive power: They receive their power from breaker side CTs.

Faulty trip units should be your #1 concern. NETA recently did a study that suggested that 1/4 breakers that are currently in-service have faulty trip units installed. I believe for the most part, this study was based on 600V air circuit breakers with older dash-pot style trips installed.

Having nearly 100 breakers reach our shop on a monthy basis, we have observed #'s higher than NETA's 1/4. We noticed that nearly 50% of molded/insulated case breakers and approximately 30-40% of air breakers have faulty trip units installed.

Kind of scary.