The term “breaker” as it applies to the electrical world usually means one thing, circuit breaker. The circuit breaker is designed to protect circuits. Contrary to what many believe, circuit breakers are not primarily designed to protect people from electric shock. That’s a subject for another article.
Breakers vary. They come in many sizes and types, ranging from the simplest molded case breaker to the most sophisticated types of breakers involving the newest current and voltage monitoring technology.
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Many people ask what part of the breaker is the most vulnerable to wear and tear. That is difficult to say because it depends so much on the environment and the type of use they are subjected to. In a poor environment for instance, (oily or dirty air) breaker mechanisms can become stiff, hampering the physical opening of the breaker. That’s why the exercising of the breaker during scheduled maintenance is so important. The importance of this cannot be overstated.
Breaker contacts themselves, while designed to open under load conditions, often become pitted causing an increase in contact resistance over time.
A breaker failure can take many forms and can be the result of many things. When a breaker fails in service, it can often lead to expensive down time. MIDWEST is your best source to find a breaker replacement. Since 1977 we have helped many customers through breaker emergencies in short order. Call our expert engineering and breaker support team for your breaker needs. If you are looking for a new, used or reconditioned breaker, we are sure we have what you need.
Three answers, NO and NO and NO. This is a big deal for us. MIDWEST does not sell old, used, or obsolete circuit breakers, bus plugs, transformers or other electrical equipment to an end user, ie the consumer, unless it has been properly serviced, reconditioned, tested, and passed Quality Controls. We strongly recommend no one buys old electrical equipment “as is.” That could be very dangerous. There are many “listing” companies and auction type sites that sell “as is.” For example, eBay does not warranty the used and old electrical equipment sold through their service. They provide a great service, but they do not provide a warranty on the specific used electrical equipment sold on eBay. The same may be true with services that just list equipment. The only people MIDWEST will sell electrical equipment “as it,” are other qualified electrical dealers that have proper Quality Controls. Old, used, or obsolete circuit breakers, bus plugs, transformers, and switchgear have too many dangerous failure modes to be sold without proper testing. MIDWEST does not just process orders. Anybody can do that. And many do. We actually have a name for that. We call it TC, Trained Chimpanzee, work. You could train a chimpanzee to put old circuit breakers into a box.
We add value. Our staff of engineers and technicians service, repair, recondition, and test electrical equipment for a living. We’ve done it for over 30 years. That is what we do day after day. And it is what we think others should do if they are going to sell something. “As Is” is just scary. When electrical equipment gets unhappy, it can fail with a boom and a flash. And that can hurt.
MIDWEST was testing power circuit breakers for a large manufacturer. The electrician working with us thought we were joking when we said we were putting 6000 amps through his 2000 amp main circuit breakers. We told him to grab the bus from the test set to the breaker and he could feel the vibration and heat from 6000 amps. He could hear the loud hum of the test set and the vibration of the old circuit breaker used in their foundry. He wouldn’t touch it until we touched the bus first. He had that strange look of “I see it, but I just don’t believe it.” We told him the output of the high current test set was going into a direct short and the output voltage was only a couple volts. We had him measure the output voltage with a voltmeter. Then he understood what was happening. It doesn’t take much voltage to push a lot of current through a dead short.
Buy 1200 Amp Square D Circuit Breakers
We had a conversation with a maintenance mechanic. He said he was a carpenter one day and an electrician the next, so he needed a little advice. He had some plastic circuit breakers that got washed down during clean up and, after they dried off, they looked great. But he wanted to know if he could still use them or if we could tell if they were okay. They were small single pole circuit breakers, a couple 200 amp circuit breakers, and one 1200 amp breaker. We call these molded case circuit breakers, but they are what everyone typically just calls circuit breakers. They also had some old obsolete bus plugs and some small transformers used for emergencies, that he just threw out. We told him to also throw out the little breakers and the 200 amp. Actually we told him to smash them so nobody would be tempted to reuse them. We have torn apart old and new circuit breakers after water damage and they are nasty inside. You do not want to reuse them. Very dangerous… Even if they worked mechanically, they could easily fail to interrupt load and turn into fireworks. We told him, if he wanted to, he could send us the 1200 amp breaker and we could take it apart and see if it could reliably be reconditioned. The chances of that are less than 50%. The real concern is whether or not the over current trip element in the circuit breaker got wet. If it did, it is very time consuming to take it apart and restore it to perfect working condition. And the quality control tests after the repair of a trip device are also time consuming. Many new circuit breakers have electronics which make reliable reconditioning after water damage almost impossible. One could do a simple clean up of a water damaged breaker and test it and it may pass all the simple routine tests. But internal inspection shows immediately that the circuit breaker, especially the circuit breaker trip device, is not reliable. We have seen water damaged used circuit breakers pass the basic insulation resistance, contact resistance, and over current tests, but fail our own additional special quality control tests. The internal inspection shows them to be in horrible condition. We find rust, free water, mud, and usually slime. If you have water damaged circuit breakers, just destroy them so no one thinks they are okay and tries to reuse them.
Buy Medium Voltage Air Circuit Breakers
We have always said, if you can’t do any maintenance on your circuit breakers, then at least exercise them whenever you have a chance. All circuit breakers, whether Square D, GE, Westinghouse, anyone’s, are much more reliable if they are exercised. High voltage or low voltage, they all need to be exercised. It’s the cheapest, easiest maintenance there is. It may not be real sophisticated, but it sure works. We saw this proven again during a plant maintenance shutdown. In this case the medium voltage vacuum circuit breakers had not been touched for 5 years, outdoors, cold winters, no heaters. Nearly all the lubricated mechanical operating parts were very stiff and many of the circuit breakers just would not operate. The good news is the breakers would have tripped open, but nobody in their plant was going to get many of them to close again. It was an old fashioned job of cleaning off the hardened lubricant and re-lubricating cautiously. Too much lubricant is a big problem in many facilities, especially one that does maintenance twice a decade. And one more note. Certain large old molded case circuit breakers, especially those used as main breakers, are extremely vulnerable to stiffing up if they are not operated a few times.
MIDWEST was asked by a maintenance foreman “why his computer went off’ even though it was on a UPS when they lost power. He said they had a brand new circuit breaker trip and within a couple minutes his computer went blank. His UPS just died the first time he needed it. When we asked why the new circuit breaker tripped, he just smiled and said “OE.” OE (Operator Error) usually means “We know why but don’t want to say, so don’t ask any more questions.” Used, obsolete, General Electric, Westinghouse, Square D, Cutler Hammer, used, obsolete, and even new circuit breakers by any mfg. are not designed to protect you from OE.
We explained that a small UPS on a single computer usually is sized to provide power long enough to “save” whatever you are working on and then “shut down” your computer properly so you don’t lose anything. The UPS also keeps the computer on if you have a brief outage of a few seconds because of things like a storm or utility switching. The UPS on my computer will keep the computer and monitor and small light on for 12 minutes. Yes, we’re Engineers, so we actually tested it. Twelve minutes and 27 seconds, to be precise. Here’s a big tip! Plug the monitor into the UPS also. It is not easy to properly shut your computer off when the monitor is blank. And if you don’t have an office window, we suggest adding a small desk lamp to the UPS. But a small UPS on a single computer is not designed to outlast OE.
Larger UPS systems will provide more power or power for a longer time. In any case, UPS systems are only a temporary source of power to critical equipment or to safety equipment. Sometimes a UPS is used in conjunction with an automatic transfer switch. The “Automatic Transfer Switch” (ATS) transfers a circuit or panel of circuit breakers from the normal power source to another power source or generator. When an ATS switches, there is a momentary power loss, so computers will still shut down, unless there is a UPS on the computer to provide power for that fraction of a second it takes the ATS to switch from one circuit to another.
The maintenance foreman’s UPS worked properly. He didn’t realize the UPS would provide backup power for only a few minutes.
Circuit breakers are unlike fuses as they are designed to open and close all three phases at once. This is a definite plus as the power can be restored after the system problem has been corrected. But even circuit breakers have their warts. They can be slower acting than fuses and sometimes one or more of the poles can fail in the ‘open’ or ‘closed’ position. If they have not been maintained for years, they could act even slower than usual or worse they may not react to a faulted condition at all. This could result in the same kind of overheating condition you could experience with two out of three fuses providing some power to a machine. You know where one fuse blows or ‘goes’ prematurely and the other two hold and then you slowly cook the machine’s motor to death. Why? Because the power from the remaining two phases, if it will spin the motor at all, will not be able to turn the fan blade on the motor shaft fast enough to provide adequate cooling.
Best remedy to keep circuit breakers fit is to routinely open and close them to keep the mechanisms moving a few times, maybe ten or so times, so all of the moving parts break through any accumulated buildup of grease and grime. Remember just because a machine is not moving does not mean the power is turned off.