Advancements in power electronics to higher power levels and faster switching times
allow new machine and systems designs, but also create higher stresses on electric
machinery insulation. High performance, pulse-width modulated (PWM) inverters are
now available for medium voltage drive systems, and are being considered by the U.S.
Navy as they move to the "all-electric" ship. If this process is to be successful, a
necessary component will be to understand the impact of partial discharge (PD)
generation on electric drive systems.
Out of the many PD influencing parameters, voltage level, voltage rise-time,
switching frequency, and temperature were chosen to be investigated with regards to their
influence on PD generation in a comprehensive research project in the Motor Systems
Research Facility (MSRF) at Oregon State University (OSU). The tests were performed
on representative propulsion coils employing two different 4160 V insulation systems
and were evaluated by both an optical and electrical PD detection method.
A highly flexible test configuration was developed, capable of adjusting each of the
four test parameters independently over a wide range of appropriate values. The
developed test program enabled the analysis of the influence of the parameters on the
generation of PD, as well as an evaluation of the test coils and PD instrumentation used.
It is concluded that, as expected, voltage level is the most significant parameter
affecting PD production. However, there is a surprising interdependence of rise-time and
pulse-width that requires further investigation. Multiple-cycling tests are seen as
appropriate to determine the effect of temperature.
Based on the subjective nature of the findings from the test program an improved PD
instrument is proposed, which would increase the capabilities and objectivity of the PD
detection process. / Graduation date: 2004
|Date||25 July 2003|
|Contributors||Wallace, Alan K., von Jouanne, Annette R.|
|Source Sets||Oregon State University|
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