Physical Acoustics Corp. awarded phase II of EPRI collaboration for detecting acoustic emission sources in gassing transformers

Princeton Junction, NJ, Oct. 8, 2002 — MISTRAS Holdings Group announces that its USA Member, Physical Acoustics Corporation (PAC) has completed a Phase I effort and has been awarded the Phase II follow-on contract for an EPRI Tailored Collaboration project.

This project has developed the technology and procedures for testing power transformers with Acoustic Emission (AE) in order to detect, locate and assess thermal and electrical faults inside gassing units.

Along with its other USA Member, Quality Services Laboratories, Inc. (QSL-Plus), over 60 transformers were tested in Phase I. Initial efforts to classify AE signals, as well as additional parametric sensors, have led to a refined procedure for in-service testing and post-test data analysis.

The development of signal classification included a joint effort with Rensselaer Polytechnic Institute and Professor Robert Degeneff.

Phase II work continues as PAC and QSL-Plus have started testing additional transformers for sponsors at their substations throughout the U.S. In addition, a new effort has been initiated to develop a means of evaluating Load Tap Changers (LTC) and Circuit Breakers. The LTC evaluation will involve the use of AE sensors together with accelerometers provided by a third USA Member, Vibra-Metrics.

This has already resulted in the modification of our existing Digital SPARTAN (DiSP instrument) to integrate accelerometer signals (low frequency and long duration) for comparison with higher frequency AE signals (high frequency and short duration).

“We believe that the results of the Phase II work will give the industry a new tool to evaluate the severity of faults in transformers and to extend this capability to LTCs and breakers,” says Barry Ward, EPRI’s project manager.

To participate in Phase II, interested utilities should contact Barry Ward at (650) 855-2717 or e-mail

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