Archive

Posts Tagged ‘general electric’

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.

 

 

Removing Cover from an Energized Breaker

November 19th, 2010 Comments off

 

MIDWEST had a customer call and ask if it was okay to remove the cover from an old 400 amp circuit breaker, live. Our Infrared Scan indicated the load side connection was overheating. They wanted to repair it, but didn’t want to turn the power off to the whole panel board. They needed to remove the cover of the circuit breaker to make the repair and thought they could just remove the four screws holding the cover on and carefully remove the cover. We explained politely that they were crazy to try such a thing. This was an old molded case circuit breaker and the arc chutes for this breaker were not fastened in place as they are in some breakers. In addition, the arc dividers were metal and they were held together with an insulated band. On some of these breakers we have to tape the band to hold the arc dividers together or they just fall apart. So the danger would be that you remove the cover with the line side still hot and one of the arc chutes falls out and the metal arc dividers fall apart. It would be almost certain that one of the metal arc dividers would short a stationary contact to a moveable contact and cause a horrific arcing blast, arcing fault.  Depending on the instantaneous, ie fault, setting of the main breaker, the fault might last for seconds and result in tremendous damage to the equipment and expose anyone nearby to serious injury or death from an arc blast. Because the fault is on the line side of the breaker, it wouldn’t take much to create a panel board bus fault. This is a good way to get someone seriously injured or killed and a good way to destroy a whole panel board. To remove the cover off any circuit breaker with the line side hot is a very bad idea. But to remove the cover of some of the older circuit breakers, with the line side hot, is just crazy because of the construction of the breaker. Inside molded case circuit breakers there are other devices that may fall out when you remove the cover. Besides all this, there may be something defective inside the breaker, just waiting there, for the first unfortunate person to take the cover off, and then it falls apart or breaks completely. You could get very unlucky. We call these things incipient failures and they can be some of the most nasty and dangerous defects in electrical equipment, because you are not expecting them. This is true whether it’s a Square D, Cutler Hammer, Westinghouse, GE General Electric, or Siemens circuit breaker or any other breaker manufacturer. Turn the main power off!

Circuit Breaker Infrared Scanning Disagreement – Lugs

October 27th, 2010 Comments off

Infrared Scan of a Circuit BreakerWe read about a disagreement between two bloggers over whether or not infrared scanning, or thermography, was needed if you torque tightened the wire connections to power circuit breaker terminals during routine maintenance.  What occurred to MIDWEST were all the possible deficiencies we find in old, new, and replacement circuit breakers, using infrared scanning, that have nothing to do with whether or not the load terminals were tight.  One of the nasty deficiencies is when the cable lug in an old circuit breaker is very tight, but the lug is overheating because the screw, holding the lug to the breaker output tab, is loose. We’ve seen brand new circuit breakers and replacement circuit breakers fry the load side tab of the breaker so bad that the breaker had to be replaced. This is true for new or old Square D, GE General Electric, Westinghouse, Siemens, Cutler Hammer, ABB, any manufacturer. It has nothing to do with a specific circuit breaker manufacturer.

 

Sometimes the lug is welded to the tab from the arcing between the lug and tab. There is a very sophisticated test one can perform during a maintenance outage to check for this defect. First, check for voltage at the load and line side of the de-energized circuit breakers. Don’t care that the main breaker is off and all the feeder breakers are open.  Check voltage anyway.  You are checking for something that shouldn’t be, not for something you know should be.  We, rather I, have personal experience with getting my hand blasted because a breaker was back fed. Very bizarre set up, unbelievable, just waiting to injure someone.

 

After checking for voltage, carefully and gently try to move the conductor coming out of each phase of each circuit breaker.  You are trying to see if the cable is loose in the lug and you are trying to see if the lug is loose, moves or turns, in the circuit breaker. You are not trying to force it to move. Just use enough force to see if it is loose in the circuit breaker. If the lug itself is loose, the cable or cables will need to be removed from the lug; The mounting screw for the lug properly tightened; The cables properly reinstalled; And the cables tightened in the lug. Again, don’t be too forceful. On small breakers, you can always make the lug move. Repeating, you just want to use enough force to see if the lugs for that old obsolete circuit breaker are loose.

 

If the conductive interface, between the lug and the circuit breaker, is damaged from severe overheating or arcing, the defective circuit breaker may need to be replaced. Sometimes the damaged area can be repaired.  MIDWEST does not recommend replacing power circuit breakers while the switchboard is energized. Be safe. Turn things off. Check for voltage everywhere.

General Electric Circuit Breakers

March 12th, 2010 Comments off

MIDWEST carries General Electric Circuit Breakers. Whether it’s a new, reconditioned, or used breaker, we are sure we can provide just the breaker you need. We stock thousands of General Electric circuit breakers in our inventory.

 

MIDWEST reconditions General Electric circuit breakers. Worn or damaged breaker component parts are tested and replaced if necessary as part of our quality control program. Over current devices can be retrofitted with electronic devices to assure state of the art over current protection. A low voltage air circuit breaker is disassembled. Insulating and current carrying members are cleaned and inspected and replaced if necessary. The breaker is reassembled and then put through a rigorous testing procedure to make sure everything properly checks out. The breaker would be tested for contact resistance, insulation resistance, and the over current devices would be tested to ensure they operate in accordance with the manufacturer’s trip curve specifications. Typical basic overcurrent functions would be long time, short time, and instantaneous pick up and trip capabilities. Some breakers contain ground fault capability as well.

 

Click Here for General Electric Circuit Beakers

 

Our staff is always excited to take your phone call and answer any General Electric Circuit Breaker questions you may have. We are proud to have served the electrical community since 1977, also the year the first Star Wars movie was released, (no connection between those events). Whatever your circuit breaker needs may be, we are sure we are your best solution. Our engineers have many years of experience with circuit breakers and power distribution equipment and they are always happy to answer any question you may have.

General Electric Circuit Breaker

February 22nd, 2010 Comments off

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.