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Posts Tagged ‘Siemens 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.  

Circuit Breaker Broken Handle, Blasted Contacts

February 23rd, 2011 Comments off

 

KD3400 Cutler Hammer Circuit Breaker For Sale

KD3400 Cutler Hammer Circuit Breaker For Sale

We grabbed another circuit breaker out of one of the junk breaker barrels. This one was a Cutler Hammer KD3400.  Again, at first the breaker looked clean and happy. But it only took a second to realize the operating handle was broken off. It takes a pretty hard blow to break the handle off a Cutler Hammer circuit breaker. Handles can be easily replaced. But further inspection revealed serious carbon residue in the area of the line side terminals. You could wipe it off but if there is enough to be visible on the outside, there is something seriously wrong inside. Most of the screws were still missing from the cover, so a technician had removed the cover for inspection of the interior of the circuit breaker and put the cover back on with only a couple screws. A quick conversation with the technician reveal that the arcing contacts were destroyed on two poles and two main contacts were seriously damaged. There was heat damage to pole pieces and arcing damage to the interior insulating, dielectric, material. This Cutler Hammer KD3400 circuit breaker was trash. The breaker did not need to be tested. It was rejected based solely on the visible damage to the operating mechanism, main contacts, and arcing contacts. Square D, Cutler Hammer, GE General Electric or Siemens circuit breakers, it doesn’t make a difference. When this happens, they all fit into the same junk barrels.

 

 

Circuit Breaker Trip Device – Hidden Defect

February 2nd, 2011 Comments off
 
Square D PAL362000 Circuit Breakers For Sale

Square D PAL362000 Circuit Breakers For Sale

MIDWEST asked our Switchgear Engineering Technicians for an example of a molded case circuit breaker that had a hidden defect that could only be found by experienced testing.  We find many used circuit breakers that have defects that can be found by a close visual inspection.  Sometimes the defect may not be obvious but an experienced Engineering Technician knows where to look and would find the problem. In the business of repairing and reconditioning circuit breakers, we find about every possible problem that can occur. Whether we are reconditioning a replacement Westinghouse, General Electric or Siemens circuit breaker, many of the problems are the same. But we also frequently find hidden defects that could only be detected using proper testing.

 

 

For this example, let’s just use a replacement Square D PAL362000 circuit breaker. The breaker was reconditioned, which involved removing the cover to thoroughly inspect and maintain the interior of the Square D circuit breaker. The technician was immediately suspicious because he detected the slight smell of an overheated circuit breaker. Once you get that smell in your nose, you never forget it in the future. Even a small whiff tells you there may be a problem. In this case everything visible was in very good condition. There were no signs of overheating at the contacts or the line or load side breaker terminals. But the contact resistance test results indicated very high resistance on the center pole. A DLRO, digital low resistance ohmmeter, was used to locate the problem. The usual location is either the contacts, the bolted connections to the trip device, or the line or load side terminals or lugs. In this case the defect was inside the trip device. And a close sniff of the trip element confirmed it. MIDWEST performed an additional test, a high current test, to determine the voltage drop and therefore the resistance in the trip device on the center pole. Even though this replacement Square D circuit breaker looked just great, the trip device was defect and had to be replaced.

Scrap Circuit Breakers

December 23rd, 2010 Comments off

 

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.