Detection of magnetic fields using leading power factor

摘要

An electricity meter includes a sensor circuit, a measurement circuit, a leading PF detection circuit and a control circuit. The sensor circuit is operably connected to detect voltage and current provided to a load, and generates corresponding voltage and current measurement signals. The measurement circuit is configured to generate energy consumption information based on the voltage and current measurement signals. The leading PF detection circuit is configured to generate a first value representative of a phase difference of the current measurement signal with respect to the voltage measurement signal, and to generate a leading PF detection signal responsive to determining that the first value corresponds to a leading power factor that leads unity power factor by more than a predetermined threshold. The control circuit stores an indication in memory responsive at least in part to the leading PF detection signal.

主权项

1. A system for use in an electricity meter, comprising:
a sensor circuit operably connected to detect voltage and current representative of, respectively, voltage and current provided to a load, the sensor circuit configured to generate a voltage measurement signal based on the detected voltage and a current measurement signal based on the detected current, the sensor circuit including a current sensor susceptible to measurement error due to application of an external magnetic field of sufficient strength thereto; a measurement circuit configured to generate energy consumption information based on the voltage measurement signal and the current measurement signal; a leading power factor (PF) detection circuit configured to generate a first value representative of a phase difference of the current measurement signal with respect to the voltage measurement signal, the leading PF detection circuit configured to generate a leading PF detection signal responsive to determining that the first value corresponds to a leading power factor that leads unity power factor by more than a predetermined threshold, said predetermined threshold corresponding to an amount of power factor variance caused by presence of measurement error in the current sensor due to application of an external magnetic field; and a control circuit configured to obtain the leading PF detection signal and store an event indication in memory responsive at least in part to the leading PF detection signal.