Need advice for a 275 ZW Transformer

If your running the transformer near max load for a long period of time it will heat up and may trip the circuit breaker which is a thermal device.  Taking the cover off reduces the ambient temperature of the ZW innards which may stop or delay the circuit breaker trip under marginal load conditions.

Thanks for the tip, but the light comes on when the transformer is first turned on and I try to run an engine.  That's why I think the cover is applying pressure to something.

Hi`, with the transformer unplugged,  try putting a slightly thick piece of cardboard into it lying flat and put the cover back on, if the card board has any marks on it, that should tell you if the cover  and the inner parts touch, i had the same problem and this worked for me, good luck, Phil

Thanks for the tip.  I tried a different technique, but I think I found the problem.  I think the wire that connects the circuit breaker was rubbing the metal mounting bracket.  I was able to trip the breaker like this when I had the cover off.  I slightly adjusted the wire, so I hope that takes care of it.  It appears all the insulation was on the wire, so I don't why this was happening.  Maybe the insulation is poor quality.  I plan on upgrading the breaker anyway, so I might change the wire at that time.  Again, thanks for the help.