Overheated buss

[ptonsparky]

I help at this small industrial on occasion. Their electrical mainentance person is usually up to most challenges but is in hospital at the moment recovering from bypass surgery.

He installed this used breaker mid summer of last year. I don't know the details as to why or if the buss was damaged at that time or not. The buss connections seem to be tight even now so the damage could be from poor breaker contacts.

Question is do you feel I need to replace this buss section? It feeds a Size 5 part winding start 480V starter about 40-50 years old. Cutler Hammer.

 

[jrannis]

It looks to me as though the breaker has a problem. Is the picture of the line or load side?

 

[ptonsparky]

Line side of the breaker & Yes the breaker is toes up. Will fly one in as soon as we locate one. Question is will this overheated buss contribute to an early failure of the next breaker? I can scan it when we get it going again but I would like to give the district manager a heads up now for future down time if needed. I have a hunch the buss will have to be custom made.

 

[iwire]

If I was called in for this my recommendation would be that both that bus finger and breaker should be replaced ASAP.

They can pay now or they can wait and pay much more later with unexpected down time.

 

[brian john]

This is cut and dry basic, "A" phase line side termination connection. If the damage WAS LESS I might recommended FOP test. But you are way beyond that, this will only get worse and FAST.

 

[j-box]

bad buss

bad buss

As iwire stated and just by looking at the discoloration on the fingers the problem goes beyond just a bad breaker, the buss fingers have severe damage due to overheating. if u only replace the breaker the problem will still remain and u will only damage another breaker and more.

 

[ptonsparky]

OK, pretty much agreed the buss finger needs to be replaced, now who knows where I can get one or have it made?

Two of me could stand inside this enclosure.

 

[captaincrab55]

OK, pretty much agreed the buss finger needs to be replaced, now who knows where I can get one or have it made?

Two of me could stand inside this enclosure.

Also let them know that "infrared testing" could locate problems before they cause problems...

 

[j-box]

Ur best bet is a breaker broker/electrical surplus company.

 

[captaincrab55]

OK, pretty much agreed the buss finger needs to be replaced, now who knows where I can get one or have it made?

Two of me could stand inside this enclosure.

I think Power Con in Baltimore Md could make them..

 

[mdshunk]

CH is pretty good about maintaining prints on all their old stuff. There's about a 50/50 chance that buss piece will be in stock someplace, but if not, you can put in a factory order to have one made. That can take weeks and weeks, often times. The breaker is pretty easy to source, since that looks like a pretty standard frame size. I've never asked CH for a print for parts, but I know that Square D will often give you dimensioned prints for parts if you want to have one made locally on short notice.

 

[brian john]

Used breaker dealer there are tons of them or IM me and I can get you a lead on one. Copper bus, most metal fabricating shops can make the bus needed.

 

[220/221]

The buss connections seem to be tight

Key words "SEEMS to be".

Classic case of loose connection.

On the installation, sometimes a bolt will appear to be tight but it's just the threads locking up for a variety of reasons. Sometimes the phone rings and distracts the mechanic before he can finish tightening it. It may have been OVER torqued and stripped.

I can't tell from the photo but generally you can clean those up.




I looked more closely at the picture and the affected terminal looked tweeked. It looks like the B and C phases of the breaker are installed BEHIND the bus while the A phase is installed in front.

Anybody?

 

[coulter]

Note to posters saying, "Replace": What are you seeing in the picture that says the copper is damaged?

Unless the copper is eroded on the contacts surfaces, consider removing all three bus connections, having them cleaned and silver-plated.

As for CH having dimensioned prints, I've found they will if the stuff was built to the "Switchgear UL Spec", and won't if it was build to "Switchboard UL Spec". That is for current production equipment. I really don't know about 50 year old gear.

Last time I dealt with replacing bus parts in old equipment (30+ years), it was a search to find current production standoff insulators that were the same height. I had some new bus made per sample (local fabricator) and them silver-plated. Worked pretty well and was weeks faster than anything the factory could offer.

You have a tough one here. This is the second CB replacement and the buss is overheated. I suspect anything you can do is a good thing. Consider having the replacement CB contact resistance tested and if marginal, have it refurbished - but I also suspect you already knew that

Let us know what happens. Good Luck

carl (with a a lower case "c")

 

[quogueelectric]

It apears that A phase is pushed forward

It apears that A phase is pushed forward

From the picture A phase may just not have been tightened. After the joint has been melted through the bolt it may seem to be tight now but it is probably just welded . I cannot tell fully from the picture but I do believe that the awful colors are just from the material insulating sleves melting on the copper. If the copper itself is not melted you should be able to remove the buss detail and clean it up on a wire wheel back to its old lustre. This definitely looks like a loose connection however it could have originated at the other end of the bus detail where it ties onto the main busbars a factory mistake. If you are going to attempt to clean up this detail you will also have to replace the destroyed insulating sleves to do the job right and make sure that the contact surfaces are flat and clean not pitted and burned. Copper melts around 2000 degrees farenheight so a lot of other stuff around it will melt or ignite before the copper actually does making a big mess

 

[quogueelectric]

bus detail

bus detail

I looked more closely at the picture and the affected terminal looked tweeked. It looks like the B and C phases of the breaker are installed BEHIND the bus while the A phase is installed in front.

Anybody?

I see what you are talking about now A bus detail seems to be behind the threaded plate of the breaker connection thereby the bolt socked up tight into the breaker contact and the buss detail was just sitting loosely behind it with the bolt running through the unthreaded hole of the bus detail. NICE!!!!

 

[templdl]

Being familiar with some of the older Westinghouse assemblies I don't recognize it. What is the product or assembly type? There's a long shot that I may be able to provide some direction.

That also looks like and old Westinghouse assemble with a L frame beaker, LB3400 or LA3600. If it has a interchangeable trip the first thing that I would do is see if there was damage done to the moving and stationary contact.
Remove the power, remove the cover and with the contacts in the open position examine the ?A? phase contacts for heating. It is not unusual for the heat a line side connection to be conducted to the stationary contact to the moving contact which heats the moving contact spring that holds the moving contact firmly against the stationary contact. The temper is taken out of the spring, which weakens it, and contact pressure is reduced which causes the contacts to heat.

 

[ptonsparky]

It is an MC3800F with a 600Amp trip. Breaker was installed correctly as far as buss placement.

Not a fun room to work in it is about twenty feet long with MCC on both sides, one entry and about 32" working space between the two. Can't open the main without opening the enclosure door first. At least the trip button worked. Line side of it shows overheating as well. Job security.

 

[76nemo]

Overdrawn??

Overdrawn??

No thermographer?

 

[electricalperson]

looks like a loose connection to me also. put a torque wrench on it and see if it was torqued down to the manufacturers reccommended torque. the bus will probably have to be replaced unless you can clean it up, re tap it and get a new bolt