GB1297814A - Improvements in or relating to fault detectors - Google Patents

Abstract

1297814 Protective arrangements V S POLULYAKH V N KHODKEVICH V G YAKOVENKO and V S KILDISHEV 7 Jan 1970 772/70 Heading H2K An arrangement for detecting faults in the rotor circuits of the exciter of a brushless machine, comprises a stationary induction pickup unit 1 in which a pulse is induced as each rotor circuit passes the unit, a signal distributing unit 2 having a plurality of output channels and operative in response to drive pulses to cyclically couple each channel in turn to the pick-up, means 3 for providing a drive pulse just prior to the passage of each one of the circuits except a datum one, past the pick-up, and means 4 for providing a datum signal just prior to the passage of the datum circuit past the pick-up, the datum signal resetting the signal distributing unit to initiate a fresh cycle. The induction pick-up unit 1 may comprise a U-shaped core with windings on its limbs and positioned close to the path of the rotor circuits, and may include an amplifier. The other units 3, 4 may each include a toothed rotor on the machine shaft the toothed rotor co-operating with a U-shaped permanent magnet having windings. The toothed rotor of the unit 3 has a plurality of teeth corresponding to the number of circuits less one, and the toothed rotor of the unit 4 has a single tooth. The signal distributing circuit 2 may comprise a binary counter and a diode matrix, its output channels being connected to a control unit 5 having an amplifier, relay and signal lamp for each rotor circuit, and in addition to indicating a defective circuit and its position, supplies signals to an automatic control and protective system for the exciter. The rotor circuits are protected by fuses, the arrangement responding when pulses are not induced in the pick-up 1 by one or more rotor circuits.