I have been working with MV, 600v motor starters and trying to get them in better operating condition. One thing I tried was to clean the contact pads on a wire wheel. I noticed immediately following cleaning visible arc flash from the contactor cover holes(See link, 6 small holes). Operation is otherwise normal and efficient. Is this normal/safe? I see this as acceptable in there is a small point where the high volts and clean pads would arc the atmosphere gap, before physical contact from engagement. However, I want to ensure that I am not making a mistake. The contact pads appear to be solid silver braised onto copper arms. In this case I would consider continuing this regularly as Preventative Maintenance. However, I want to know for sure.
Am I safe in what I am doing and should I continue to do it for restoring these starters? Or am I building a “bomb” that will later become a bigger issue? What are your thoughts, concerns, advice?
The specific starters are Eaton A200M2CAC Model J
. I have included some photos of the contact feet.