Assessment of insulation condition of generator stator bars based on velocity of ultrasonic waves

作者：Hao YP^*; Xie HK; Wang GL; Jia ZD

来源：IEEE Transactions on Dielectrics and Electrical Insulation, 2003, 10(3): 539-547.

• stator bars insulation
• insulation diagnostics
• ultrasonic
• dissipation factor
• partial discharges
• capacitance
• scanning electron microscope

The velocity of ultrasonic waves, which were launched using the pulse-echo method and propagated in a stator insulation, was measured to assess the insulation condition of the stator bars. A statistical minimum velocity (V-min) and a statistical average velocity (V-av) were computed for a new and three sets of stator bars which were in operation for 16, 18 and 23 years. After velocity measurements, several conventional electrical parameters such as dissipation factor, capacitance, and partial discharge were measured, and microscopic examinations of dissected insulation of tested bars were examined with a scanning electron microscope and an optical microscope. Experimental results showed that V-min and Vav decreased and more microscopic defects were formed in the insulation with increasing operating time of the stator bar. For the three sets of aged stator bars, the insulation conditions based on V-min and V-av were consistent with those assessed by measuring electrical diagnostic parameters. Therefore, V-min and V-av were used to assess the insulation condition of large generators. The measurement of ultrasonic waves may offer a broad prospect for stator insulation diagnosis.

• 出版日期2003-6
• 单位西安交通大学