| 摘要 |
The metering system and method provides an electronic power meter for simultaneously producing digital pulse trains proportional to power and to VARS or Q. In the preferred embodiment, the metering system employs delta-minus-sigma modulation of the voltage signal which produces a modulated output signal used for gating the analog current signal, multiplying voltage and current. The product of voltage and current is then supplied to another delta-minus-sigma modulator (90), which serves as a convertor outputting a pulse train. The converter (90) produces separate pulse trains for each polarity of the power being measured. VARS or Q readings are produced by delaying the output of the modulator (30) by a selected amount to produce the necessary voltage lag, after which the delayed modulated signal is supplied to another multiplying gate. A second converter (90) is used to output VARS and Q. A metering method is also disclosed, as well as an offset compensation system (70, C1) for use with metering systems. |
