The data is then plotted on a log log scale and analyzed using Rotary special

The data is then plotted on a log log scale and

This preview shows page 8 - 10 out of 14 pages.

fixed intervals as per a sheet provided by Rotary. The data is then plotted on a log-log scale and analyzed using Rotary special software to reveal a wealth of information that conventional IR-PI tests does not provide. Benefits: ± Detailed analysis and single test that determines machine winding condition with respect to presence of contamination, its nature and location, resin condition, leakages within machine, lack of contact of coil with core, charge storage and such other physical insights. ± Goes beyond IR-PI tests, which are dependent only on leakage mechanisms, by also studying charge storage and transport mechanisms. ± Evaluation of present machine winding condition without opening the machine.
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ROTARY ELECTRICAL SERVICES LTD RESIDUAL LIFE ASSESSMENT (RLA) SERVICES 2.2 CAPACITANCE AND TAN DELTA ANALYSIS The PDCA test described above is based more on surface physical phenomena. For an in depth understanding of insulation characteristics there is a need for ac tests. Tan delta & Capacitance Analysis is one such test. Tan delta is indicative of the in phase component of current drawn by the insulation, in other words, represents the power dissipation in the insulation system. This test is conducted at various voltage levels upto the rated phase voltage of machine, by using a transformer ratio arm bridge balance method to record the tan delta & capacitance values. These curves are later analyzed using special Rotary software for before discharge inception voltage to reveal physical abnormalities like lack of contact of coil with core, interfacial polarization, presence of contamination, looseness of coils/wedges and after discharge inception voltage to reveal presence of partial discharges and its location. Benefits: ± Detailed analysis that determines machine condition with respect to presence of contamination, resin condition, presence of air-gaps/voids within insulation, lack of contact of coil with core, looseness of coil/wedges, interfacial polarization and such other physical insights. ± Tan delta values may change depending on several factors intrinsic to machine and even environmental conditions and thus its trending may not reveal any information. Rotary technology calculates certain parameters like void volume content etc and trend these parameters instead of absolute values to reveal developments of any abnormality. ± The test is one time test and does not depend on previous tests. ± Provides explanation to conditions even before discharge inception voltage. ± Does not just reveal the presence of PD but also its location. 2.3 NON-LINEAR INSULATION CURRENT ANALYSIS (NLIC) The test is supplementary test to both PDCA and Tan Delta & Capacitance Analysis. In this test, an AC high voltage is impinged on the insulation system and the current, drawn by the insulation, is subjected to a special non-linear analysis. Due to charge storage mechanisms, this current is replete with harmonics. The relative content of harmonics, predominant harmonics and the pattern of harmonic magnitudes is indicative of anomalies in the insulating system such as ionic activities in slot region, presence of contamination, partial discharges. The test provides a
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  • Spring '18
  • Strength of materials, Tensile strength, Stator, RLA

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