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Posts Tagged ‘Cutler Hammer Circuit Breaker’

Square D MAL361000 Circuit Breaker May Take 5 Minutes 40 Seconds to Trip

January 20th, 2011 Comments off

 

Square D MAL361000 Circuit Breaker For Sale

Square D MAL361000 Circuit Breaker For Sale

MIDWEST had a customer call because they had an old Square D MAL361000 and it took forever to trip when they had a serious overload problem. He bet it took 3 minutes. This brought up a common misconception concerning how circuit breakers provide protection. When we provide Hands-On Safety Training, this is one of the items we are sure to cover. First of all, whether Square D circuit breakers, Cutler Hammer circuit breakers, GE General Electric circuit breakers, or Siemens circuit breakers, they are not designed to protect people directly. They are designed to protect connected equipment, yet not nuisance trip due to a non harmful transient event. By protecting equipment, circuit breakers consequentially protect people. His old Square D circuit breaker may have taken over 3 minutes to trip and it may have performed the way it was designed. Breakers have a performance specification called a “Time Current Curve,” TCC. In basic terms, whether Westinghouse circuit breakers or ABB circuit breakers, they do not trip immediately at the trip setting. A 1000 amp circuit breaker does not trip right away at 1000 amps or even 1500 or 2000 amps. As a matter of fact, an old 1000 amp Square D MA circuit breaker may have a trip range of 45 seconds to 340 seconds when overloaded with 3000 amps, 300%.  In basic terms, it should not trip in less the 45 seconds and may take as long as 340 seconds to trip. This may seem crazy but, again, it is designed to protect the equipment connected to it while not nuisance tripping. The same breaker would have an instantaneous setting which would determine at what current value the circuit breaker would trip immediately. But, if that setting is over 300%, ie 3000 amps, the breaker would cook for a long time before tripping.  By that time you can smell the breaker overheating.

Emergency Replacement Circuit Breaker for Christmas

January 12th, 2011 Comments off
 
General Electric SEDA24AT0100, 2 Pole, 100 Amp

General Electric SEDA24AT0100, 2 Pole, 100 Amps

Sometimes we get calls from a customer that is in a real jam and has limited resources or time to get out of it. And sometimes these problems are over small pieces of electrical equipment, such as a replacement General Electric circuit breaker, two pole 100 amps. We got such a call just before Christmas. A home owner’s electrician needed a replacement circuit breaker, 2 pole 100 amps, for an old home. The existing circuit breaker would not latch closed. They had limited information on the old circuit breaker. They would have changed the whole panel but they couldn’t get it done before Christmas.

First we explained they had to contact the electric utility because they were changing the main breaker for a house. We sent them two styles of recondition circuit breakers because their information was not specific enough. We told them to use the replacement circuit breaker that was correct and to return the other breaker to  us. Their ‘replace circuit breaker’ problem, as they called it, was solved and they had lights for Christmas. They returned the other breaker to MIDWEST. Their problem wasn’t because they needed an unusual replacement Square D circuit breaker or replacement Cutler Hammer circuit breaker. Their problem was because the location was Hawaii.  It was a big problem for a small customer, but it made everyone feel great that we took care of them for Christmas.

100% Rated Square D 2000 Amp Circuit Breaker

December 15th, 2010 Comments off

MIDWEST lost a battle with the maintenance dollar.  A manufacturing plant had a 2000 amp Square D circuit breaker that was loaded to over 1800 amps, sometimes hitting 1900.  We detected the heavily loaded breaker during an Infrared Scan of the facility.  This was an old Square D circuit breaker mounted in a tap box feeding a 2000 amp bus duct. The local contractor recommended they just replace the breaker with a 100% rated breaker. He said they could use Square D, Cutler Hammer, or General Electric, whoever was cheapest and would fit. Because of the bus configuration, it only made sense to use the same Square D circuit breaker. The customer bit on the idea that just replacing the old circuit breaker would solve their problem and save them a lot of money. We strongly disagreed. Replacing the circuit breaker would make zero difference, in this case. The old Square D molded case circuit breaker was an 80% rated breaker.  More recent replacement Square D circuit breakers, same frame, model number, current rating, were 100% rated, ie 2000 amps. The 100% rated replacement circuit breaker was specified 100% if it was in an enclosure with a much larger volume than the old breaker. In other words, to achieve the 100% rating, the breaker must be in a much larger enclosure so as to properly dissipate the heat generated from 2000 amps. This all makes sense. But to just replace one breaker, whether GE General Electric, Cutler Hammer, Siemens, or Square D, with a 100% rated breaker and not address the installation requirements to achieve the higher rating can be a waste of dollars.  A quick check of the old and new circuit breaker specifications, will tell what the installation requirements are. This is the technical added value that is often ignored, or just not known, in too many facilities, as experienced personnel disappear.

            This facility decided to replace the circuit breaker, but later transferred load off the bus duct.

Cutler Hammer Circuit Breaker

March 3rd, 2010 Comments off

Cutler Hammer, a venerable name in breakers, bought out the Westinghouse distribution and controls business unit in 1994. This acquisition included the Westinghouse circuit breaker division. MIDWEST carries many types of Cutler Hammer/Westinghouse breakers. A popular Cutler Hammer breaker is the KDC3250 thermal magnetic breaker. Thermal magnetic refers to the type of over current device of the breaker. The thermal element (heat) is responsible for opening the breaker under an over current (long time) condition. The magnetic part is responsible for opening the breaker in a short circuit (instantaneous) condition.

Our engineering and technical sales staff at MIDWEST gets really excited when the phone rings in anticipation of a breaker question. Our expert staff has many years of experience. They are very happy to help you solve your breaker problem.

For the complete line of Cutler Hammer circuit breakers, give us a call or visit our web site at www.swgr.com. We have a huge inventory of used breakers in stock and ready to go. While you have our representative on the line, ask about our other electrical products we handle.

MIDWEST has been in the beakers service, sales, and testing business since 1977, the same year the Yankees won the World Series pennant for the 21st time. There is no connection between the two events that we are aware of.

MIDWEST maintains a huge inventory of breakers in stock. Whether you are looking for a new, used, or reconditioned breaker, we would be happy to help you find it.

Our office is open from 7:00am to 6:30pm CST.