Partial discharges in 3-core belted power cables

It is noted that partial discharge testing of three-core belted-type cable using single-phase test voltage may lead to large errors as compared to the actual three-phase service conditions. The method of energizing the cable and the configuration of the discharge detection circuit largely affect the magnitude of the error. Eight different test circuits are discussed with respect to their usefulness in the laboratory as well as the field. Attention is paid to the similarity of the electrical stresses in the single and three-phase circuits. To this purpose field calculations were performed on different single-phase test circuits to determine a design that meets the three-phase field patterns at its best. Three circuits are selected as being suitable for a correct single-phase partial discharge measurement