Abstract: In a circuit arrangement for measuring a starting of rotation of a generator having an exciting winding and three-phase windings, a voltage regulator regulates an output voltage of the generator by influencing an exciting current, the three-phase windings are connected to one another at a point, one of the phase windings is connected to ground via a first resistor, another of the phase windings is connected to ground via a second resistor, a voltage across the first resistor is evaluated as a rotational-speed-dependent alternating voltage, this voltage is compared with a threshold voltage, and the starting of the rotation of the generator is detected when the measured voltage exceeds the threshold voltage.

Abstract: The battery charging apparatus includes a generator, main voltage regulator, an auxiliary voltage regulator, at least one consuming device and a protective circuit having circuit portions for recognizing and signalling faults via a charge control lamp. The generator output voltage is rectified with rectifier bridges containing Zener diodes. Voltage comparison to threshold values and logic circuitry for processing the comparison results are used to determine the presence of faults in the operation of the battery charging apparatus. The fault detection device detects conduction defects in the main voltage regulator and/or interruption in the generator excitation circuit. The logic circuitry determines whether simultaneously both a supplied voltage exceeds a threshold value and the main voltage regulator is turned on longer than a predetermined time interval to indicate its continuous operation.