ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by tortuga - 03/28/24 05:57 PM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
0 members (), 260 guests, and 19 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 2 of 3 1 2 3
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
The coils can only "smoke" if there is electricity to them, so there must be a wiring error.

Most mechanically held contactor coils are not designed to be "on" all of the time so they have coil clearing contacts. Is there a Normally Open contact in series with the open coil and a Normally Closed contact in series with the close coil?

What is the manufacturer and type of contactor?

Joined: Sep 2006
Posts: 98
A
Member
I agree with JDB, all of the lighting contactors I have dealt with have coil clearing contacts to prevent just the situation described. Most of my contactor exposure has been Square D, but ASCO, GE & others pretty much use the same scheme of things. Because of the mass of the armature it takes a lot of current to hold in the steel, so as an economy measure(cheaper coils, less energy consumption) they are designed to take the power off the coils as soon as the contactors change state. I would look at the mfg. wiring diagram very closely and not try to rewire them - the ones that I have worked on in dozens of contactor panels, some with 25 or 30 contactors, have the neutral switched as a part of the manufactured assembly. A well meaning electrician in Atoka, OK, rewired a mess of these contactors 'cause the factory wiring was against his principles, and upon energization, smoked several thousand dollars worth of contactors before the store opened, had to replace all the coils...

Joined: Nov 2005
Posts: 507
M
Member
sparky,

is it a GE360CR? or in that family? We had a similar problem with a 360. Worked fine for about 10-12 yrs, then started to burn up control wires and coils. We actually found several cracks on the magnet and a few other places on the main contactor. It seems that someone had replaced the on of switch with a standard 3 way (leaving continuous power to either the on or off contactor.) that and the daily pounding of drawing in that load, finally did it in. We replaced the unit with the newer model (much smaller and lighter)

Joined: Jul 2004
Posts: 625
S
Member
Wild-ass guess: "Something different at night": That could be the photocell.

If the photocell results in a continuous application of power to the coil, that might cause it to burn up, as I believe that type of coil is designed to only be pulsed for long enough to switch between the on and off positions.

[This message has been edited by SolarPowered (edited 10-04-2006).]

Joined: Nov 2005
Posts: 507
M
Member
solar, it is. One of the problems we found with ours was that the 3-way switch was used. Causing the same issue. Constant power.

Joined: Dec 2002
Posts: 59
S
Member
It's a GE # CR160MC7502A Pics can be seen here http://pg.photos.yahoo.com/ph/sparky_806/album?.dir=6465re2

photo-cell controlls a relay. the relay controls the open/close coils on the contactor. according to my GE rep, everything is correct.
Richard

[This message has been edited by sparky806 (edited 10-04-2006).]

Joined: Oct 2004
Posts: 806
Member
sparky806:

Putting my thinkin' cap on and looking at all the pics, in particular numbers 16 and 18, what I'm seeing is badly pitted/burned contacts (second from left) and serious burning of the moveable pole piece that appears to be pulled in by the action of the coils.

Best guess here is that the burned pole piece is causing chatter (does the contactor buzz even when the coils are disconnected?) which is frying the contacts, causing the smoke.

Try replacing the contact set and the pole piece assembly, (items in pics 16 and 18), I'm willing to bet a case of your favorite beverage that'll fix the problem. [Linked Image]

Good luck and keep us posted...


Stupid should be painful.
Joined: Oct 2000
Posts: 2,723
Likes: 1
Broom Pusher and
Member
Kind of looks like a 100 Amp Lighting Contactor drawing >100 Amps across the Contacts.

Looks more like an alignment problem is to blame here, which is keeping the Contacts from seating properly when closed.

This would be from installing the Lighting Contactor assembly over a non-flat surface, then tightening everything down - causing the Contactor's back mount plate to be bent; resulting in the Contacts being misaligned (not a solid and full connection) when they are closed and latched in.

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
Ok..... First, you're dealing with a now antiquated contactor design for this application. (Although they still make them) If this were a newer design unit it would have self cleaning /wiping contacts, and for that matter it would be switching loads individualy with a number of smaller relays. Thats a lot of amperage to switch this way. If you're not going to go all the way and just suggest a full upgrade of the contactor, which may require a different panel or enclosure to the side, those contacts are garbage at this point. mxslick's suggestion is a good one, but but unless they make good FAST and SOLID contact in the future this problem will only repeat....
[img]http://us.a2.yahoofs.com/users/43db47d7z80dafa65/6465re2/__sr_/fe69re2.jpg?phg6LJFBKpQ0cf_a[/img]
As a temporary fix to further troubleshoot, take some 400 grit, and then some 600 grit sandpaper to them and polish them up. Then some contact cleaner to get rid of the residue. Put the contactor together and test it with no load outside the panel. And check to see if this thing is operating properly with a smooth solid connction, and that it has good tension on the contacts when closed. It may be that the mechanism is binding....

Now.... It also may be that the 120 you see when it not loaded by the contactor is much less under the load of the contactor. And this might not be enough usable power to actuate the contactor fully. And may be the cause of those arching contacts.... (Also how are the secondary contacts, are they OK?) One cause of this might be what appears to be a loose nuetral by the discoloration of the conductor below. As this seems to be the panel nuetral, you might have some other problems all around soon...
[img]http://us.a2.yahoofs.com/users/43db47d7z80dafa65/6465re2/__sr_/82a1re2.jpg?phIKMJFBr1K3eBhH[/img]

Although I think the smoke you saw was from the coils, was really just drifting from the contacts, the fact that you got voltage at them while it was diconnected sounds odd. Is it at all possible that there is not a fault in the coils to ground? What where you measuring this 120 to? Ground of the can, or the nuetral? Do you have excessive voltage ground to nuetral? (While the loads are on.)

Either way it sounds as though you have a brain teaser - let us know what it eventually gets found out to be.

[This message has been edited by e57 (edited 10-05-2006).]


Mark Heller
"Well - I oughta....." -Jackie Gleason
Joined: Dec 2002
Posts: 59
S
Member
Great advice and ideas from everybody, but I am still banging my head into the wall. Here is a time line of replacement parts in this panel:
6/03-- 1st new contactor. Lasted 1 week
6/03--new coil kit. GE warranty. lasted 5 minutes
6/03--new coil kit. GE warranty.
8/03--new contactor. GE Warranty
2/04--new contactor. GE Warranty
6/04--new comtactor. GE warranty
1/05--new contactor. GE warranty
9/05--new coils. GE warranty
12/05--new contactor. GE warrant
8/06-- new coils GE warranty

I have had GE involved in this since June of 2003. They have sent field techs and checked out the building electrical system and found no problems. I can't really see the sending me this many new parts under warranty if they didn't have a known problem with this contactor.

e57, I would love to install a new lighting panel and it has been suggested to the customer more than once. I can't get them to do it yet. Anyway, thanks for the advice guys. I will let you all know what the "new field tech" from GE comes up with today.
Richard

Page 2 of 3 1 2 3

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5