43-1974 - IEEE Recommended Practice for Testing Insulation Resistance of Rotating Machinery
Description: This document describes the recommended procedure for the measurement of insulation resistance of windings of rotating machines rated 1 hp, 1 kW or greater. It applies to synchronous machines, induction machines, direct-current machines, and synchronous converters. It applies to armature windings and field windings. The document describes insulation resistance characteristics of rotating-machine windings, the manner in which these characteristics may serve to indicate the condition of the winding, and the testing procedure for obtaining insulation resistance values. It gives the recommended minimum value of insulation resistance of alternating-current and direct-current rotating-machine windings. The Appendix gives maintenance information relative to dry-out procedure.