ECN Forum
Posted By: sparkync 3 phase lighting contactor - 11/23/11 12:00 AM
I checked outside pole lighting that is not working. I'm not getting 120 volts down to the coil on a 3 phase 480 volt contactor. There is an over-ride switch that over-rides the photo cell. I get voltage through another set of relays ( called unlock relay on the j box cover) down to a set of N/O contacts on the contactor. But it is not going through the contactor contacts to the coil. I know I'm missing something somewhere, because there is another contactor that is right beside this one and it is working, but when I measure for voltage on that coil, I'm not getting but around 74 volts. I measure to ground from each of the terminals and still do not get any reliable voltage, yet the coil is pulled in. Am I going crazy?? Coil pulls in but no voltage reading on the coil. I check my meter on the line side of 480 volts and, yes, my meter is working. It looks like on the contactor that is working, they have a jumper from another j box to a neutral wire, bring a neutral straight to one side of the coil. It is a Westinghouse A202K3CAMP2 lighting contactor. I've tried to pull it up on the net and can't find it. One of my supply houses said that Cutler Hammer bought out Westinghouse. Pretting obvious I'm a little dark on the operation of this kind of contactor. Any help would be appreciated. Thanks again.. Steve
Posted By: HotLine1 Re: 3 phase lighting contactor - 11/23/11 02:37 AM
Sounds like you have a mechanically held contactor. Voltage applied to 'on' coil pulls contactor in, latch holds contacts "ON". Voltage applied to 'off' coil, or 'unlatch coil. & contacts open.

Are you taking voltage readings with a solenoid type (Wiggy) tester, or a DVM? You may be reading phantom voltages.

Try the CH website tech area for a mechanically held lighting contactor schematic; it has to be close to the old Westy.

Posted By: sparkync Re: 3 phase lighting contactor - 11/23/11 03:50 AM
Yes John, after the clouds passed in my head, that's what I figured was happening. I don't work to much with starters and contactors but occasionally. I'm using a fluke digital meter. When testing the voltage on the coil when the manual over-ride switch is flipped, I didn't even see any voltage reading. It's probably happening too fast to show up on my meter.
On the other contactor that's not working, I can't seem to figure out why the power is not getting down to the coil. It comes to the top of the contactor N/O contacts when the over-ride is flipped, but is not making it down to the coil to pull the coil in. I don't guess I understand the inward workings of the contactor too good. I'll look again on the tech page and see if it comes more clearly. It didn't help my thinking capacity any though, when the maintenance man at this place sticks his hand in the access hole of the light pole with 480 volts inside with the power on with no gloves. I worked on one a few days earlier and found a 277 volt connection with the tape peeled off. Very scary. I guess people like that think they're brave. With no offense to anyone, I think it's stupid.
Posted By: sparkync Re: 3 phase lighting contactor - 11/23/11 04:15 AM
John, by the way, where do you find the tech section on the CH site. I don't seem to be able to find it. Thanks again.. Steve
© ECN Electrical Forums