A New High-Speed Thermal Wattmeter

The thermal converter discussed in this paper is of the type which produces at its output terminals a millivoltage proportional to the polyphase power connected to its input terminals, the connections being made as for a wattmeter. High-speed response is secured through the use of a new circuit network wherein the thermocouples function also as heaters. Response time of the order of one-half second is obtained. The use of nickel-alloy transformer cores saturating at overloads broadens the over-load capacity of the thermal unit itself. Thermal converters of this type are widely used in the summation of power.