| 摘要 |
<p>VAL-107 A power monitor including a high power shunt connected in series with an electrical load to develop a signal proportional to current which is then modulated. A second signal proportional to the voltage across the load is developed by a voltage divider network. The two signals are applied as inputs to an electronic multiplier which produces a modulated output signal which is proportional to the power being dissipated by the load. The output signal from the multiplier is fed through an isolation transformer which passes the modulated power signal, but blocks the high load voltage. The power signal is then demodulated, filtered and displayed digitally on a meter. This signal is also provided as an analog output. An oscillator synchronizes both the demodulator and modulator, the oscillator drive of the modulator being isolated. When the load is a three-phase device, two such wattmeter modules are employed to measure the current and voltages associated with two of the three legs of the load, the output of the demodulators of the two modules are then summed, passed through a filter and displayed as a single power reading. During the summation process, the demodulated output signal is electrically scaled to read as horsepower, kilowatts, or percent of full scale.</p> |
