AVTech conducted service project performing partial discharge (PD) measurements in Germany at one of the larger power plants. The reason for AVTEch’s project was the earlier results of transformer diagnostic that needed a follow-up. AVTech’s aim was to verify the earlier findings and, if possible, locate the source of the PD.




The measurements were performed by the AVTech team. The transformer had a rated power of 600 MVA. 45 sets of measurements were recorded covering the high and low voltage sides of the transformer.

Significant acoustic activities that to a high degree of certainty can be traced to partial discharges was discovered in mainly four areas on the high voltage side of the transformer. The high apparent energy and frequency acoustic signals indicate high levels of partial discharge within the transformer. Several areas in the transformer were identified as potential sources of the partial discharges; those areas should be inspected closer.

This resulted in recommendations to monitor the evolution of the partial discharges. Follow-up acoustic measurements to determine the development of partial discharges over time and/or to follow up the effectiveness of any service performed was advised.



Optimize maintenance process and costs

  • Early identification of PD activity allows for advance planning
  • Replacement of assets can be done without significant interruption of the production
  • Order new assets for replacement ahead of time


Reduce risks

  • Avoid catastrophic asset failure and power outages
  • Increase safety for people


Improve financial returns

  • Get the most out of the investment by prolonging the transformer lifetime due to the timely maintenance
  • Avoid unplanned transformer downtime and associated costs
  • Optimize asset management and strategies for asset development and replacement
  • Reduce the insurance costs



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