The use of the dynamometer wattmeter for measuring the dielectric power loss and power factor of the insulation of high-tension lead-covered cables

The use of the dynamometer wattmeter for measuring the dielectric power loss and power factor of cable and capacitor insulation is not new, but dates from about 1890. Dynamometer wattmeters as available today are suitable for making these measurements. Care and attention must be given to their application. The usual methods of application are: 1. Compensated dynamometer wattmeter method, with air capacitor, 2. Inductance variation method (phase-defect compensation method), with air capacitor, 3. Series resistor and wattmeter method, 4. Resonance wattmeter method. Comparative measurements of dielectric power loss and power factor of cable samples indicate that results are being obtained with the dynamometer wattmeter wherein the probable departure from the true value is within from 10 to 20 per cent. There is need for an effective means of standardizing any measuring equipment. Study of the calorimeter method for this purpose seems desirable.