Ampgard contatcorss
Ampgard contatcorss
(OP)
I use several Cutler-Hammer AMPGARD vacuum-break starters (7200 volt/400A) in a 2 high cubicle. What I find disturbing is the ground scheme. When the contactor is opened and load disconnected, the contatcor is then shut to short the load side and ground. But the ground bar only grounds to the enclosure structure, not solidly to a ground bus. The path for this ground is thru sheetmetal screws and the like, most of which have paint under the heads. Continuity from the ground bar to my actual ground has been as high as 30 ohms. Normally I look for 0.1 ohms or less.
The resolution has been proposed to clean off the paint and get good continuity. I am going ahead with a ground lead directly from that ground bar to my ground bus (once I figure out where to connect it), to get a good solid ground when the load is grounded thru the contactor.
This is shipboard ungrounded system, and I have a good ground connection from hull to ground bus.
Anyone else use these contactors and noticed the same configuation?
The resolution has been proposed to clean off the paint and get good continuity. I am going ahead with a ground lead directly from that ground bar to my ground bus (once I figure out where to connect it), to get a good solid ground when the load is grounded thru the contactor.
This is shipboard ungrounded system, and I have a good ground connection from hull to ground bus.
Anyone else use these contactors and noticed the same configuation?





RE: Ampgard contatcorss
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If we learn from our mistakes I'm getting a great education!
RE: Ampgard contatcorss
This is standard Cutler Hammer panel. That is what really surprises me. The response is that the ground path is sufficient as it is not carrying a fault, only potential grounding of the load circuit. But hey, that is from a salesman. On our next installation, later this year, I am gong to reject the installation which should force them into a formal answer.
RE: Ampgard contatcorss
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RE: Ampgard contatcorss
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If we learn from our mistakes I'm getting a great education!