Electricity meters.

摘要

An electricity meter for metering the amount of electrical energy supplied by a power supplier to a power consumer is provided with means for detecting the presence of an external shunt (50) which has been connected to by-pass its internal current sensing means (22). The detecting means, which in one embodiment comprises a differential current sensor (32, 34) for sensing the difference between the respective currents flowing to and from the consumer via the meter, is arranged to operate a circuit breaker (44) and/or to compensate the energy measurement of the meter, and/or to provide a warning to the supplier. The differential current sensor also senses when current is being taken between the live wire and earth on the consumer's side of the meter.