So, I work on medium to large ac and dc electric motors, and recently had a 74 kw (roughly 100 hp) dc motor come in for a rebuild. We usually induce a voltage into the field and interpole coils with a tool called a growler to test for even voltage drop across the coil system. But recently, we had one go back to the customer, and upon start up, an interpole coil grounded. It passed all of our qa tests, and still failed. We spoke to a gentleman who has been in the industry for around 35 years that now works for EASA, and he said the growler test is okay, but mostly induces voltage on the iron and not the coil itself. Therfore, I've been looking online for possible test circuits that I can build using a potentiometer that will allow me to hook up the two motor leads, and apply 0 volts at first, and ramp slowly up to approximately 12 volts ac power to the coils. Does anyone have any tips, or ideas to help design such a circuit? Any thing will help!
Thanks!
Thanks!
