This book was THE "Bible" (mandatory study) for everyone working in an Electrical Apparatus Service Shop that I worked at for a number of years. Self-teaching is great, but it goes a lot faster and a lot further if it is supplemented with GOOD references, and this is the best (for beginners and intermediate, anyway). WELL worth the investment.
Interpole coils on large DC equipment are so low resistance that a low-ohmmeter is necessary for testing (not a standard, or even "good" quality multimeter will do) for shorts ... and a hi-pot tester for grounds (which might be intermittent during running only). Lots of basic education in DCM&G circuit testing will provide the fundamentals necessary to follow the simplest process of elimination for such troubleshooting.
