A free 3000 amp circuit breaker! This sounded too good to be true when MIDWEST’s Switchgear Shop made the announcement. And, of course, they were just being wise guys. It was another opportunity to spin up the Engineers a little, and it worked. What they meant was the breaker was shipped loose on the pallet, in other words free. It seems MIDWEST was shipped an old 3000 amp power circuit breaker for maintenance and testing. The breaker was properly wrapped, boxed, and strapped to a sturdy piece of plywood. The plywood was on a sturdy pallet. Looked like someone did a good job shipping this fairly large power circuit breaker.
But, the breaker was free, loose on the pallet, because the plywood was not fastened to the pallet. It could just slid around, slid right off the pallet. We’ve seen a lot of different techniques used to ship old and new circuit breakers. Some good ideas and some bad. In this case, someone went all out, but still missed the mark. Fortunately there was no damage and we added this information to our training file.
An all too frequent scenario experienced by customers working in power distribution involves an air circuit breaker which after having tripped open fails to close again. When racked-in and the breaker charged it may trip free when the close button is engaged.
Running down the list of possible factors, there are several key culprits which come to mind. Topping the list is the breaker racking-in interlock mechanism. This interlock system is designed to ensure the breaker is fully in the racked-in position, the contact fingers fully engaged with the bus contact stabs, before closing. What often happens is all too typical. The close tolerances designed in the racking-in mechanism can get out of tolerance through use if you so much as breathe on it wrong, or so it may seem. Even out of the gate as new equipment, they can be quite finicky birds requiring some TLC to keep them working smoothly.
The fix can be as simple as removing the front cover of the circuit breaker and lubricating the racking mechanism allowing its resets and mechanicals to function properly. The mechanism’s dogs can get stiff preventing the mechanism from seating properly.
In other cases we look for evidence the breaker may be over-racked in the racked-in position, throwing the interlock system out of alignment.
The circuit breaker proper may be out of alignment in its cell. This is very bad and runs the risk the load side connections (the finger clusters) may not be seated properly on the bus stabs. This is a nightmarish scenario if somehow the breaker manages to close and becomes energized.
When part of a good maintenance program, an air circuit breaker can be expected to delivery good reliable service for many years to come.
MIDWEST has seen about every old obsolete circuit breaker there is. We worry about the dangers of some breakers to those not familiar with circuit breakers. Some of these dangers are not present very often, but when they are, they could be lethal. Here is a quick example of one such danger with molded case circuit breakers. These are the plastic looking circuit breakers. This danger usually occurs with three phase breakers. The breakers have a plastic like toggle that is pushed up and down to turn a circuit breaker on and off. Some circuit breakers with this toggle like handle are designed such that there is a metal stud that extends from the breaker into the toggle to give it support. Occasionally the toggle breaks off leaving a visible metal stud sticking out from the front of the now defective circuit breaker. This metal stud looks innocent enough. You might even be tempted to use a tool on the stud to turn the breaker off or on. Don’t. On some breakers, the metal stud is actually energized at the full voltage of the middle phase. That’s right, the metal stud is hot. Shocking! And if you get between it and ground, you could be killed. Whether old, new, or obsolete, if you find a breaker with a broker handle and there is an exposed metal stud, have a qualified electrician check it out. The exposed stud would be hot when the breaker is closed, not when it is open, unless the breaker is back fed. This is shocking news about some circuit breakers with broken handles.
General Electric Circuit Breakers offers many high quality molded case breakers for your power distribution needs. MIDWEST is your single best source for referencing a General Electric Circuit Breaker. Whether new, used, new surplus, or reconditioned we carry a huge inventory of General Electric Circuit Breakers in our warehouse. Our engineering and technical team gets really excited when the phone rings with a question about a General Electric Circuit Breaker.
Here at MIDWEST, we have been testing and maintaining breakers since 1977. You might say, we know breakers like a mother knows her baby. Along with General Electric Circuit Breaker, we offer many types and sizes of breakers in stock and ready to ship. Whatever breaker problem you may have, we are sure to solve it for you. Our complete line of breakers is online at www.swgr.com.
One quick word about our service: As part of our quality control program, all our breakers are put through a rigorous testing procedure before they are shipped to our customers. This assures our customers the high level of service they have come to know from MIDWEST.
While you have one of our people on the phone ask him about our other electrical products we carry. We handle a complete line of power distribution equipment. Just give us a call and speak to us soon. We still answer the phone with a live body. Our office is open from 7:00am to 6:30pm CDT. Our technical team looks forward to speaking with you.
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.