A COMPUTER-CONTROLLED LOAD LOSS STANDARD FOR CALIBRATING HIGH-VOLTAGEPOWER MEASUREMENT SYSTEMS

A computer-controlled load loss standard, based on the current-compara tor technique, for calibrating high-voltage power measurement systems is described. Measurements can be made at any power factor from zero l ag through unity to zero lead, positive or negative power, at voltages up to 200 kV, currents up to 1000 A, and 50 or 60 Hz. The load loss s tandard features current-comparator-based components including a high- voltage active divider, a unity-gain integrator for producing an accur ate and stable reactive component, a high-current transconductance amp lifier with the ability to provide a highly accurate current to a circ uit that is operated at high voltage, and a computer for control and d ata reduction. In a laboratory environment the load loss standard has an uncertainty of less than 10 ppm for both magnitude and phase. Howev er, when used for on-site testing/calibration, due to temperature effe cts, its uncertainty is increased to less than 100 ppm in magnitude an d 10 ppm in phase.