• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.199-202
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• 2002

During normal operation, partial discharge(PD) tests were performed using turbine generator analyzer(TGA) in high voltage motor. Epoxy-mica couplers are installed at motor terminal and analyzed PD signal using TGA. #A motor stator insulation is good because small partial discharges are detected. PD pattern show that PD occurs in insulation. PD of #B motor is larger than that of #A motor and PD pattern show that positive PD larger than negative PD. It means that PD occurs between insulation and slot. And A phase PD magnitude of #B motor is large and high compare with any other phase. Therefore wedge, core and slot of #B motor need to check and repair.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.452-454
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• 1999

In this paper, sample coils for stator form-wound winding of traction motor were made for the accelerative thermal degradation composed of heat, vibration, moisture and overvoltage. In progress of test periods, diagnosis tests such as insulation resistance, dielectric loss and partial discharge were investigated. Reliability and expected life were evaluated on the insulation system for 200 class traction motor considering various environmental stress.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.606-610
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• 2003

The 200 class insulation system which adopted to traction motor have excellent dielectric strength but weaken to thermal stress therefore deterioration phenomena analysis according to thermal stress is necessary. Accelerated thermal aging tests have been used to determine thermal reliability of stator coils used as traction motor in electric multiple unit. The conventional aging test is carried on according to IEC 60034-18-31 and IEEE Std. 275-1992. Variation in insulation resistance, P.I, capacitance, dielectric loss($tan{\delta}$) and partial discharge are measured during the aging cycle. Sample coils for traction motor were tested by accelerated aging test which composed of heat, vibration and moisture. Reliability and expected life were evaluated on the insulation system for traction motor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.43-46
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• 2004

Recently many research activities on the diagnosis of stator winding insulation of high-voltage motors have been reported. Most of them utilize a trend analysis of partial discharges. In this paper, a novel on-line monitoring system for an insulation diagnosis is proposed. This system displays magnitude and phase angle distribution of partial discharge. The partial discharge activities can be interpreted more precisely by these techniques.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.481-486
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• 2006

In this paper, a new on-line high-voltage motor monitoring system is proposed. This system monitors the insulation condition of the stator winding by on-line measurements of partial discharge (PD). And this system displays magnitude and phase angle distribution of PD. Sensor, CC (Ceramic Coupler) is used for PD measurement. PD signals are continuously measured and digitized with a A/D converter to build the database of the high-voltage motor's insulation condition. Also, this system can communicate with the central monitoring system via RS-232, 422, and TCP/IP. This helps more efficient operation and maintenance of the high-voltage motor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1073-1074
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• 2011

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1524-1526
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• 2000

Two stator windings for high voltage motor(rated 6.6kV) were manufactured with mica tape/varnish(No. 1). and mica tape(No. 2). Electrical tests included ac current, tan $\delta$ and partial discharge magnitude in these stator windings. Electrical properties showed that No. 1 stator winding was better than that of No. 2. Microstructure properties were conducted using scanning electron microscope(SEM) in the cross section of the straight stator windings. SEM results indicated that the mica tape interface of No. 1 stator winding was larger than that of No. 2 stator winding.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1183-1186
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• 2004

Degradation and insulation failure of traction motor depend on the continuous stress imposed on it. And knowing on insulation condition is important thing for safety operation of EMU(electric multiple unit). In this paper, PD(partial discharge) characteristics for degradation analysis of stator coil is studied. For PD data acquisition, two models are made; one is normal condition coil, the other is aged condition coil. And PD data for discrimination were acquired from PD detector. And these data making use of a computer-aided discharge analyser, statistical and other discharge parameters is calculated to discrimination between different discharge sources. And also these parameter is applied to classify PD sources by neural networks. Neural Networks has good recognition rate for degradation of stator coil.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.230-235
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• 2012

Cases of insulation breakdown damage of water-cooled generator stator windings occur frequently due to coolant leakage and water absorption worldwide. Such serious accidents may cause not only enormous economic loss but also very serious grid accidents in terms of stable supply of electric power. More than 50 % of domestic generators have been operated for more than 15 years, and leak and water absorption problem of windings are often found during the planned preventive maintenance period. Since 2005, leak and water absorption tests have been performed for total watercooled stator windings after fully drying the inside of the windings. The results are then comprehensively analyzed. The result of the test performed by GE, a foreign manufacturer, for 141 generators showed failures in 80 of them (failure rate: 57 %), whereas in the tests carried out in Korean domestic power plants, only 14 out of 50 generators showed failures (failure rate: 28 %).

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.286-291
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• 1991

Most of the failures of rotating machine are stator coil insulation failures. The insulation diagnostic testing for high voltage motors and generators are only megger test and P. I Test which is applied DC voltage until now. But it was impossible to judge insulation deterioration status of high voltage rotating machinery by above testing. In other words, even though the megger measurement values are fairly high, they used to be failed from time to time. Therefore in order to excute reliable and detailed diagnosis of insulation deterioration for rotating machinery, the tangent delta test, the alternating current test and the partial discharge test shall be applied to the insulation diagnostic testing on site.