Thorn Emi Electronics Limited

Thorn Emi Automation Limited

David L Neasham

Steven J French

An electrical apparatus for monitoring electrical continuity includes a number of input circuits each associated with a respective arm of a multi-phase rectifier circuit the continuity of which is to be monitored. Each input circuit includes a comparator which generates a train of pulses P while an input current persists in the arm. If a discontinuity arises in an arm for a first preset interval of time a monostable in that arm generates a first trigger signal. If the discontinuity persists for a further preset interval of time another monostable, common to all the arms, triggers an alarm via a bistable circuit.

Electrical apparatus

In some industrial situations a battery charger is used to supply d.c. power to an electrical equipment, and a battery is connected across the output terminals of the charger so that a 'back-up' supply is available if the charger should fail. An indicating circuit is used to generate a warning if an open circuit condition arises in the battery charging circuit. The indicating circuit operates by monitoring the output impedance of the battery charger. If the output impedance exceeds a threshold value the indicating circuit generates a warning signal.

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Penkridge, United Kingdom

David L Neasham