Estimation of Insulation Diagnosis and Dielectric Strength in 6.6 kV Motor Stator Windings

Abstract

-To assess the deterioration condition of stator insulation, diagnostic and AC dielectric strength tests were performed on five high voltage (HV) motors (2,000 HP, 6.6 kV) for boiler feed-water pump (BFP). Two HV motors for BFP were installed per unit. Following the long term rewinding program, the diagnostic test was performed on five 6.6 kV motors during the planning maintenance period. After completing diagnostic test, AC dielectric strength test was done on the stator windings of HV motors. The AC dielectric strength test was conducted at 15 kV for one minute. Dielectric strength test and diagnostics test results confirmed that the stator insulation was judged to be in serviceable condition in the five 6.6 kV motors.

Analysis of Correlationship between Partial Discharge and Ozone Emission in High Voltage Motor Stator Windings as the Index of the Insulation Diagnosis

“…Many electrical diagnostic tests have been performed to evaluate the health of insulation systems for rotating machine stator windings. In general, Insulation Resistance(IR), Polarization Index(PI), Dissipation Factor(DF), AC current test and PD test have been conducted and analyzed to assess the soundness of insulation systems as had been shown (Kim, H. D. (2014), Kim, H. D., Kong, T. S., Ju, Y.H., & Kim, B. H. (2011), Kim, H. D., & Kong, T. S. (2012), Kim, H. D., & Kong, T. S. (2014)). Also, it is well known that the O3 is produced when the electric discharge occurs in air and studies are still going on the correlations between PD and O3 emission as works in this topic (Lépine, L., Lessard-Déziel, D., Bélec, M., Guddemi, C., & Nguyen, D.N.…”