Effects of converter pulses on the electrical insulation in low and medium voltage motors

A new IEC test specification is under development for the insulation systems used in converter-driven machines with the aim of providing manufacturers with a reliable means to quality insulation systems for use in converter-fed machines and users with confidence that the machines they purchase contain insulation that is fit for their intended purposes. Much of the qualification testing for insulation systems subject to converter voltages may be undertaken with existing 50/60 Hz equipment. However, for testing of complete coils in low voltage machines, an impulse generator and an impulse PD test set are required. For large machines, which have stress-graded endwindings, it will be necessary for a source of converter voltage to be available.