Abstract: A capacitor is connected in circuit with the output windings of an alternator in such a manner that it is charged in a first direction during selected half cycles and in a second direction during the other half cycles of the alternator alternating current output potential. During the selected half cycles, the alternator output potential and the charge upon the capacitor acting in series aiding relationship provides base drive current for a driver transistor to trigger this device conductive through the current carrying electrodes. Upon the conduction of this transistor, base drive current is supplied therethrough to another transistor included in an associated voltage regulator circuit to trigger this device conductive through the current carrying electrodes thereof which completes an energizing circuit for the alternator field winding.

Abstract: The fuse element of a thermal fuse and heater assembly is connected in series in the energizing circuit of the generator field winding of an electrical generating system between the field winding and the current carrying elements of an associated voltage regulator output switch. System potential is applied across circuitry responsive to system overvoltage conditions for completing an energizing circuit for the heater element of the thermal fuse and heater assembly. With sustained system overvoltage conditions, the heater element heats the thermal fuse element to a temperature at which the fuse element "burns out" to interrupt the generator field winding energizing circuit.