Circuit Breaker Exercising Standard

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spsnyder

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What is a good standard for existing medium and low voltage circuit breakers, disconnects, etc. as far as exercising and preventative maintainence?

Thank you in advance.
 
And, one of the best kept secrets NEMA AB4, "Guidelines for inspection and preventive maintenance of molded case breakers used in commercial and industrial applications."

I have always recommended that a breaker be exercised or two reasons.
1) To help with the distribution of lubrication within the moving parts.
2) Since the contacts do not simply close against one another but they actually rub together, the contact resistance that exists frequently reduced.

I'm not personally sold entirely on what NETA promotes, as I'm not so sure where they got some of the information that they base their recommendations on. But NETA has found a market niche that has grown by great leaps and bounds which provides a common point for anyone form maintenance firms, design firms, building owner, field service people, etc to go to.
It?s very interesting that the actual manufacturer is often ignored as well as their installation and maintenance manuals.

I frequently run into issues when one of my products is reject based upon what "NETA" standard testing and must now defend my from a manufacturer's standpoint. We do not manufacture to NETA requirements but to applicable industrial standards such as ANSI and NEMA and must be UL listed or component recognized.
I trust that I?m not being viewed as anti NETA because I believe there is a need for it. But one should exercise caution as to not view it as the ?bible.? I believe it should be used as a guideline but the manufacture should have the final word. I don?t believe that NETA should be viewed and a standard.

As a former breaker application engineer one of the questions that I address frequently was contact resistance and file testing. Yes, there are many "black and white" answers but there is also the application of common sense as well a technical knowledgeable and experience as a qualified field service technician should have. I find it very intriguing that there are all too many that turn off their brain when it comes to fact reason and logic to rely of simple black and what answers found in books and on charts.

I am now in sales and applications with a transformer manufacturer and have the same issues and problem when addressing field applications.
 
Oh yes, I don't believe that you'll find a "standard." Maybe a recommendation, yes.
Just think of how many people you will "____ off" when they have to reset all of their digital clocks.
Not trying to be funny but just when when would it be practical to "exercise" a breaker without having a planned outage?
I would like to think that's why there are no "standards." And how about all of that other stuff that is on 24/7.
Even thought I'm a believer in exercising breakers in my own home my wife would not take kindly to me if I "exercised" our breakers.
 
I knew a guy once that had this big ($20k used price) machine for testing large (400,800,1200,1600 amp IIRC) breakers. It hooked up to a 20a 120v outlet. I don't know how that thing worked (it did make a lot of noise), but the job we did for him on numerous occasions was to shut down whatever building it was he was working on and remove each breaker from the switchgear and pass to him to test (we had to use a lift to maneuver the huge things) with his big machine.

He'd turn some dials and the breaker would either trip or not trip, and we'd put it back with a sticker indicating the test date and results. We sold a few replacement breakers too based on the test results.

How you test a 3o 1600amp breaker with a 120v 20a circuit (running on a genset, no less) is still a mystery to me. Maybe someone with smarts can 'splain it to me.

I don't know what the machine was called, but I do know that one night he disappeared and so did the $20k worth of machine. The company he worked for (that owned the machine) went belly up because of that... So if you run into a shady looking guy with a big breaker testing machine, let me know where he's at...
 
jerm said:
How you test a 3o 1600amp breaker with a 120v 20a circuit (running on a genset, no less) is still a mystery to me. Maybe someone with smarts can 'splain it to me.
Click to expand...

No one said he has to test the breaker at full voltage. Your supplying the test unit with a 20 amp 120 circuit or 2.4 KW

120 volts @ 20 amp is 2400 watts or 2.4 KW.

Now what if the test voltage was 1.2 volts?

2.4 KW @ 1.2 volts will be 2000 amps.

Now understand that there may be other things going on as well but swapping voltage for amps I bet is part of it.
 
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"I don’t believe that NETA should be viewed and a standard."

ANSI would disagree with you! The NETA testing standards are recognized ANSI satndards.

NETA uses manufacturer recommendations, NFPA 70B, and RCM concepts for its maintenance interval recommendations.
 
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jerm said:
How you test a 3o 1600amp breaker with a 120v 20a circuit (running on a genset, no less) is still a mystery to me. Maybe someone with smarts can 'splain it to me. QUOTE]

Good guess iwire, but you are way off on this one.

That is called a secondary injection test set and is used to "simulate" the trip secondary current from the CT's to the trip unit. Typically most CT's on LVCB's have a XXXX:0.5A ratio so at full load the output of the CT is 0.5A. The secondary injection test set will simulate different load conditions (ex: 300% OL=1.5A) to trip the breaker, the time it takes to trip under a specific load is compared to the TCC for that trip unit. Secondary injection only tests the operation of the trip unit, trip coil, and tripping mech.

Seconday injection does not test the CT's which is why some companies/Orgs do not consider it an acceptable test, they require a primary injection test. Thats about a 2000Lb $100,000 test set that puts actual fault currents through the breaker.
Click to expand...
 
4800A isnt much, a main breaker for a 480V substation usually has a AF rating of 2000A-4000A, to test ST at 150% of setting (Assume 4X) requires around 12,000A-24,000A.

I would not buy a primary injection set with less than 30kA output. Every one for every company I have worker for has had at least 40kA output. The test set in your link would be great for CT testing or small MCCB's.

Last place i worked our 2 sets weighed 1800Lbs and 2400 lbs.
 
Zog:

Every test set for it's application.

I Own 4 of these

0-3000 amp good for small frame CBs, motor overloads and GFP testing.

1 of these

0-12,000 good for Cb's up to 1000 amps OCP.

and 1

0-50,000 amps almost all other CBs.
 
brian john said:
weight 100-1500 depending on output current.
Click to expand...

This machine was on four big wheels and was at least 4' long x 5' high x 2' thick and weighed a lot. It took four guys to get it out of the back of the truck.
 
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