Abstract: Testing appartus and method for testing a regulator for switching current to an external load device in response to applied voltage, e.g., field current of an alternator. This tester is arranged to enable accurate determination of regulated voltages and operates to apply load circuitry to simulate in a closed loop mode of operation the operation of the regulator in its operating environment. A power delay circuitry is connected across the terminals of the regulator and supplies load current to a third terminal when the regulator is turned on by charging a capacitor in the delay circuitry. When the charge on the capacitor reaches a high limit, the regulator switches off and load circuitry is switched on to ramp the capacitor voltage downwardly until the regulator again switches on. The load circuitry at that time switches off. An auxiliary power supply is effective when the regulator is switched on to supply additional load current.

Abstract: There is disclosed a testing device for a voltage regulator incorporated in a generator assembly for controlling the output voltage of the generator assembly to a predetermined value, the generator assembly including an AC generator having a field coil and an armature coil, and a rectifier for rectifying the output of the AC generator. The testing device comprises a DC power source, a variable voltage generator for supplying a variable voltage to the input of the voltage regulator, and a resistor connected between the DC power source and the field coil, whereby presence or absence of failures of the voltage regulator may be judged from a magnitude of the input variable voltage and a change in voltage at a junction between the field coil and the resistor, as the input voltage is gradually increased.