Squareback alternator testing armature

Dana67Dart said
When I have used a Megger we were looking for broken down insulation between windings and other voltage leaks.

If the insulation is broken down, as an example (10 windings could be shorted making fewer total windings), increasing current draw and reduced output

But that's just my experiance

Well you can megger from the brushes to the case, yes. That will not check for a short between turns. I've got two old hand crank Biddle meggers. I think one is 500V, and if I remember, the other is selectable, up to 1KV