Assessment of Insulation Condition in High Voltage Motor Stator Windings

고압전동기 고정자 권선의 절연상태 평가

This paper describes to access the insulation deterioration condition of the stator windings in six high voltage motors. Nondestructive tests have been carried out on stand-still motors. These tests include ac current increase rate($\Delta$I), delta tan delta(${\Delta}tan{\delta}$), and maximum partial discharge(PD). AC current and $tan{\delta}$ were measured by Schering bridge. The measurement of PD patterns were conducted using digital partial discharge detector. PD patterns were observed treeing and internal discharges in Motor 1 and 2. The stator windings of two motors were found to be in a poor condition and their were recommended to rewind. The stator. windings of four motors were judged to be in serviceable condition.