Individual local control of electrical loads - by monitoring voltage depression and current with logic circuits having trip facilities

摘要

The installation provides local autonomous control of the load of individual consumers as one means for preventing a supply system collapse. Connected between the main fuse of a consumer spur and the load is a circuit breaker (S), under the control, for example, of a microprocessor. A voltage measurement is made between fuse and circuit breaker, and compared with the nominal supply level. Current is measured on the load side of the circuit breaker, and checked for increase or decrease. The processor operates on both these signals to determine whether local load should be shed. For example, if the voltage falls below a set minimum and the current is rising the circuit breaker is opened. Reclosure follows after a set time if the voltage has recovered to nearer the nominal value. The processor may be arranged to shed part loads before ultimately ordering the circuit breaker to open.