Small transformer question
Small transformer question
(OP)
I ran into some industrial saws that I think are not properly wired. It has a transformer wired for 480 volt primary and a 240 secondary and that is all well and good. However some of the controls on the inside use 120 volt coils and there is no connection to x2-x3 on the secondary so they have to be flowing current through ground. Center tap is not grounded and one one machine they got 75v to ground on one leg and 220v on the other and was tripping a breaker after 7 years of running ok. A similar machine next to it had 120v to ground. It doesn't make since to me at all how either are working since the secondary isn't grounded. Is the power returning through the core?
https://res.cloudinary.com/engineering-com/image/upload/v1644846983/tips/transformer_xczmgx.bmp
https://res.cloudinary.com/engineering-com/image/upload/v1644846983/tips/transformer_xczmgx.bmp
RE: Small transformer question
Keith Cress
kcress - http://www.flaminsystems.com
RE: Small transformer question
There will be some capacitance to ground, making things a little different and causing some current flow and voltage to ground even without loads.