Calibrator for alternating voltage, current, and power

A computer-controlled calibrator capable of delivering AC sinusoidal and distorted waveform voltage, current, and power with an accuracy of several parts per million is described. The reference AC voltage is obtained using digital-to-analog conversion and the reference AC current by applying the reference voltage to a reference AC resistor. The phase relation is obtained digitally. A combination of feedback and error-feedforward control strategy, together with the current comparator technique for very accurate ratio measurements, is applied. The parts per million stability of the calibrator permits the use of a multiplexing program for varying the settings and for monitoring several instruments over a long period of time