Max. demand indicator for electricity meters - has electronic storage of monthly figures with load shedding and synchronisation

摘要

The max, demand indicator for both Ferraris and electronic-tyoe electricity meters, uses a storage device such as a printer, punched tape, magnetic card or tape, or semiconductor ROM to register the monthly max. values. The first month's store is not cleared until the end of the 13th month. The monthly and annual kilowatt-hour consumption figures may be displayed via a liquid-crystal or similar electronic display unit. Limit switches using triacs or relays, can be incorporated to shut down loads if the max. consumption rate is exceeded. An audio tone signalling system or a programmable ROM may be used for this. Timing pulses for accurate measuring periods e.g. 1 hour, 24 hours, 1 month, are derived from the mains frequency. Several max. demand meters may be synchronised using an A. F. power line carrier signal.