Dielectric Loss and Capacitance Measurement Test of Hydraulic Generator in Overseas Projects

HIMALAYAL - SHANGHAI - CHINA

Abstract: During measurement and maintenance of large capacitance steam turbine generator and hydraulic generator, capacitance of test equipment often falls short to adapt to characteristics of overseas project or satisfy requirements of domestic and overseas standards. To solve this problem, this study conducted analysis on application principles of series resonance device and dielectric loss measurement device first, then came up with the method of measuring dielectric loss and capacitance of hydraulic generator with composite application of series resonant device and dielectric loss tester based on measurement characteristics of the device. This method was then applied to measurement test of the general contracting project in Indonesia, test results were analyzed according to domestic and overseas standards. The result of this study proves that this method is accurate and operation-friendly, which satisfies correlative standards inland and overseas, providing practical reference for overseas projects.

Key words: overseas project, hydraulic generator, series resonance, dielectric loss tester, dielectric loss measurement, capacitance measurement

Foreword
Large hydraulic generator stator usually applies wave winding for wiring, winding of each phase consists of several series winding components. Due to electromagnetic structural characteristics (large air gap and deep stator slot) of large hydraulic generator stator, winding bar mutual inductance of stator winding, inter winding bar capacitance and winding bar self inductance are negligible compared to ground capacitance. However, measurement of generator dielectric loss and capacitance is a necessary item during construction and maintenance, this test has significant importance attached to inductance of the generator.

Common obstacles seen in overseas projects are due to different standard applied from domestic projects, plus conditions of test equipment are restricted by multiple factors, causing the test to fail. The tricky part of measurement test for hydraulic generator dielectric loss and capacitance under the circumstances of overseas project is that capacitance of hydraulic generator is generally dozens of times of fire power generator capacitance, test equipment with such capacitance is hard to find even domestically.

On account of limitations of access to series resonance device and dielectric loss tester only and no external standard capacitor available onsite for overseas projects, this article searches for test method for generator dielectric loss and capacitance measurement in accordance with overseas standard and grid requirements to measure dielectric loss and capacitance of large capacity generator with limited test equipment. Feasibility of composite measurement can be verified on basis of test result of hydraulic generator dielectric loss and capacitance measurement of the general contracting project in Indonesia.