| 摘要 |
<p>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 which has been connected to by-pass its internal current sensing means (22). The detecting means comprises means for injecting a reference signal with a generator (84) whose frequency is different from that of the AC power signal into the current sensing means (22), and means for monitoring the signal produced by the reference signal in the current sensing means for changes indicating the presence of such a shunt. The detecting means is arranged to operate a circuit breaker, and/or to compensate the energy measurement of the meter, and/or to provide a warning to the supplier.</p> |
