Partial discharge inception voltage measurement and location identification of enamel coating ribbon wire used for low-voltage motors

This paper deals with partial discharge inception voltage (PDIV) of ribbon-type enameled wire which is fabricated to increase space factor in the motor windings as compared with the conventional enameled wire. Measurements of PDIV are carried out by applying 60 Hz AC voltage. A photomultiplier tube (PMT) and a partial discharge measuring instrument (Nippon Keisokuki CD-6) are used for detection of PD signals. The measurements are done 50 times to evaluate PDIV values statistically. On the other hand, the electrical field distribution around the air gap in the specimen is calculated using an electric field calculation software (ELECTRO V80®, Integrated Engineering Software Inc. Ltd.). The resultant electric field distribution allows examination of PD location with considering Paschen curve. It is found that PD occurs in the space formed between the flat electrode and the ribbon-type enameled wire. The calculated result was verified by observing PD light emission.