1.1 This guide lays down method for the measurement of insulation resistance of armature and field windings of all types and voltages of rotating electrical machines rated 1 MW and above.
1.2 This standard also recommends minimum values of insulation resistance of windings of ac and dc rotating machines.
IS 7816-1975 history
1976IS 7816-1975 Rotating Electric Machine Insulation Resistance Test Guide