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Posts Tagged ‘Westinghouse Circuit Breakers’

Important Circuit Breaker Maintenance Tool – Wasp Spray

March 21st, 2011 1 comment

On a field service project, the customer was amazed at how much equipment we had on the large service vans. Besides the test equipment for old and newer circuit breakers and for oil filled power transformers and switchgear, we had the equipment and tools to maintain the switchgear and make many potential repairs. Plus generators, fuel and lights and much more. The customer asked, kind of as a joke, if we had anything on the trucks that was very important but wasn’t technical. This was a shutdown project where the power was turned off at 5:00 AM and had to be back on by 11:00 AM. A lot of work in six hours, including replacing one of the circuit breakers.

 

The immediate simultaneous response from two Engineering Technicians was, “Hornet Spray.”  Each truck has at least one can of hornet, actually wasp spray, in a can that will spray a stream 10 to 15 feet. We learned decades ago that it can be painful if you have a short shutdown project and open up the switchgear to access your favorite Square D circuit breakers or Westinghouse circuit breakers or new Siemens circuit breakers and you find the switchgear to be a hotel for a bunch of wasp nests. Hard to find a volunteer to take the bite clearing out wasp nests so you can replace circuit breakers. Instead, a little stream of spray here and there and you’re ready to go. No customer wants their project put at risk because of a few bees, even if they are mad. The bees that is. It’s a magic solution for a non technical problem.  So that’s something non technical but extremely important for an outdoor project to inspect, test and maintain circuit breakers and electrical switchgear. Don’t leave home without it.  

Scrap Circuit Breakers

December 23rd, 2010 No comments

 

ED3100 Cutler Hammer Circuit Breaker

ED3100 Cutler Hammer Circuit Breaker

This morning I walked past three drums of old, obsolete, used circuit breakers. All these breakers were going to the scrap heap. Actually they go to a recycling company that crushes them and recycles the metal parts. If someone was to ask what we do with the defective circuit breakers, this would be the answer.  These drums contained Square D, Westinghouse, Cutler Hammer, Siemens, GE General Electric circuit breakers and probably many other manufacturers. If a circuit breaker is mechanically or electrically defective, if it doesn’t pass our inspection and testing quality control, it gets tossed into the scrap heap, actually drums. 

If you were to look at the breakers in the drums, you would find many that look in perfect condition, some even mint. But, if you tore them apart, you might find the contacts blasted beyond any possible repair. This is found with an internal inspection, contact resistance tests, or by a voltage drop test during over current testing.  One might be surprised how many old and even new surplus circuit breakers are rejected based on the visual inspection. And, again, you would be amazed at how many new looking circuit breakers fail one or more of the quality control tests.

No one manufacturer or model, whether Square D, Cutler Hammer or GE General Electric circuit breakers, is exempt just because of the name on the label. And no breaker can be evaluated just based on its appearance. Sometimes a circuit breaker may fail a test and we really have to look hard to find the cause of the defect. Sometimes the defect may not be visible, for example a defective over current trip device.

 

So you can’t judge the condition of an old or new surplus circuit breaker by its appearance. MIDWEST is always testing new circuit breakers as part of our Acceptance Testing Services on new switchgear, a common practice for hospitals, data processing centers, and mission critical facilities. And we do find deficiencies in brand new circuit breakers.  So again, appearances can be deceptive. 

Circuit Breaker Retrofitting Shortcut Mistake

July 16th, 2010 No comments
For many years retrofitting General Electric circuit breakers and Westinghouse, now Cutler Hammer, circuit breakers was very common.  Replacing the old dashpot style over current devices with modern electronic over current protection greatly improved the reliability and the flexibility of the retrofitted circuit breaker. This was particularly true when using the newer generation electronic retrofit kits. We still run into many of these retrofitted circuit breakers today.  Typically the retrofits were well done. But sometimes we run across a circuit breaker that was retrofitted in the field, on site. This saved time and was often done quickly during shutdowns or to just save cost. Ignoring the need to maintain a circuit breaker to be retrofitted, MIDWEST never retrofitted circuit breakers on site because of the need to perform complete over current testing and special load testing after the retrofit was complete.  Companies that retrofitted breakers on site could test the breaker by secondary injection method. That would prove the new electronic device operated properly and it would prove the old Westinghouse circuit breaker would actually trip, but it did not proof test the complete system. Worse yet were occasions when we might see a General Electric circuit breaker, for example, that had been retrofitted on site and not even tested by secondary injection method by the contractor that did the work.  MIDWEST recognizes this when we are troubleshooting a circuit breaker that apparently failed to trip and we discover that it would never trip under any circumstances.  We do a positive trip test. Tough test, takes about 12 seconds. We simply confirm that the trip device will actually move the trip bar enough to trip the Westinghouse circuit breaker, for example.  And we find out it will not. This is typically just a mechanical adjustment.  But you can imagine the anger when a customer finds out that the breaker they paid 2 or 3 thousand dollars or more to retrofit fifteen years ago, was just a switch because the breaker would never trip under any conditions, other than pushing the trip button.  Period maintenance and testing would have found this. Experience and knowledge would have prevented it. Shortcuts cause problems. It wouldn’t make any difference if it was an old Allis Chalmers, Siemens, ITE, or Federal Pacific or General Electric or Westinghouse circuit breaker, the problem was with the service company procedure, not the manufacturer.