Abstract :
The difficulties which arise in the measurement of the power factor of cable samples owing to leakage over the surface of the dielectric at the ends have been previously studied, but the remedial measures suggested are not always adequate, particularly when the cable is immersed in water at elevated temperatures. Price´s guard wire, which acts so successfully in the direct-current measurement of insulation resistance, fails to eliminate all the leakage in the alternatingcurrent case. The author has modified the simple guard wire to make it effective for a.c. measurements, and in conjunction with a suitable bridge it completely avoids the error due to end leakage.
