Further Studies of Anomalous Phenomena in Dielectric Loss Measurements Using a Three-Electrode System

Further theoretical analyses show that it is the physical parameters of the guard gap region which give rise to the anomalous phenomena observed in dielectric loss measurements using a three-electrode system. A Wagner or similar guard balance, which is generally used to make the potentials at the guard and the guarded electrodes identical in magnitude and in phase, may reduce the errors caused by the bridge balance conditions, ons, but cannot alter the physical parameters inherent in the guard gap region. An interfacial dielectric layer such as vaseline between the test sample surfaces and the electrodes enhances the anomalous phenomena under certain conditions. The potential along the guard gap surface varies from point to point although the potentials at the guard and the guarded electrodes are equal in magnitude and in phase. It is the nonuniform field distribution in the guard gap region which results in electrical discharges at the sharp edges of the guard and the guarded electrodes. Experimental results are in good agreement wtih the theoretical analyses. Methods for suppressing these anomalous effects also are discussed.