Calculation of the eddy current distribution in the disk of single-phase kilowatt-hour meter by variational method

A method based on variational principles has been developed for the computation of the eddy current distribution and hence the driving torque of single-phase kilowatt-hour meters. The airgap field due to the voltage and current coils in the absence of the disk is presumed to be given, and the resultant air-gap field, as well as the eddy currents induced by it, are determined. The reaction field of the eddy currents is taken into account approximately. Global approximation is employed to yield the field quantities as expansions in terms of suitable analytical functions. A comparison is made between computed and measured torques.