Patent ID: 8283942

Claim:
An auxiliary power unit with diagnostic facilities, comprising: an alternating current generator having a direct current exciter winding and an output winding; an automatic voltage regulator for maintaining control over an excitation voltage applied across the direct current exciter winding responsive to sensed voltage across the output winding; a plurality of multimeters including multimeters providing readings for the voltage applied across the direct current excitation winding and the sensed voltage and resistance measurements for the direct current excitation winding and the output winding; the automatic voltage regulator being further connected to an auxiliary output winding in the alternating current generator for supply of electrical power; a multimeter from among the plurality of multimeters providing an auxiliary output voltage reading from across the auxiliary output winding and a resistance reading for the auxiliary output winding; and means for relating voltage and resistance readings taken with the multimeters to faults in the generator or with the automatic voltage regulator.