E-lesson

Transformer Testing Course – e-lesson #17: Capacitance and dielectric dissipation factor measurement

In this lesson, you will learn about the AC insulation test method for the capacitance and loss factor. Lesson is hosted on Master's level.

Master’s level Thursday, 27 February 2025, 6:00 PM TZ Europe/Zagreb
Master’s level

Hosted by: Balazs Sztari / Master's level

This transformer testing course lesson covers the measurement of capacitance and dielectric dissipation factor, which are important diagnostic tools for assessing transformer insulation condition. The lesson will discuss relevant standards, the theoretical principles behind these measurements, and different instrumentation and test methods. Attendees will learn how to properly prepare the transformer for testing and the key factors that can influence the test results. The lesson will also cover the specific considerations for measuring capacitance and dissipation factor on transformer bushings. While there are no strict acceptance criteria, the comparative analysis of test results over time is crucial for evaluating insulation health.

This is e-lesson #17 in Transformers Testing course, authored and presented by Balazs Sztari. It is presented on the Master’s level.

The 17th lesson of the Transformer Testing Course focused on capacitance and dielectric dissipation factor (DDF) measurement in power transformers. These measurements are crucial for assessing insulation quality during factory acceptance tests (FAT) and on-site commissioning. The session covered the relevant standards, theoretical background, instrumentation, test procedures, influencing factors, and practical applications for transformers and capacitor bushings.

Overview of Transformer Testing Topics

The current lesson introduced capacitance and DDF testing, focusing on:

  • Standard references
  • Theoretical concepts
  • Instrumentation and test procedures
  • Capacitance and dissipation factor measurement for windings and insulation
  • Testing of capacitor bushings
  • Factors influencing measurement results

About the author

Balazs Sztari

Ganz Electric

Balazs Sztari graduated as electrical engineer in Budapest. Beside of factory acceptance tests, his team performs commissioning, diagnostics and R&D tests on power transformers and rotating machines.

He is currently a member of Cigre A2.53 working group.