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Power Transformers - Dielectric Frequency Response Testing

Reduce the Risk of Transformer Power Failure with Advanced DFR Testing

Transformer Insulation Diagnostic Tool

Dielectric Frequency Response (DFR) testing is an excellent tool for diagnosing transformer insulation issues. A DFR measurement is similar to the more frequently-used power factor testing, except that power factor is measured over a wide range of frequencies, from mHZ to kHz.

DFR testing is used mainly for assessing moisture in power transformers. The dryness and condition of oil-paper insulation is a key factor in both short and long-term power transformer reliability, since moisture has deleterious effects on both dielectric integrity and insulation aging (deterioration) rates.

The relevant properties of insulation systems in an oil-filled power transformer include the moisture in cellulous material conductivity of oil, geometry of the insulaton, and the presence of contamination or other factors that affect the capacitance and loss factors of the insulation system.

 DFR testing is the most accurate method available today for estimating moisture in insulation systems.

What can Kinectrics do?

Kinectrics offers a full range of routine, type, and advanced tests for power trnsformers,. For DFR testing, Kinectrics has established specific programs for utilities, transformer manufacturers, contractors, and other users.

Kinectrics services include:

  • Performing DFR tests with voltage range of 10 V to 20 kV on 2-windings, 3-windings, auto-transformers, GSU, bushings, CTs, and PTs
  • Moisture estimates using available databases and software
  • Interpretation of power factor, capacitance and permittivity curves
  • Diagnostics such as insulation contamination assessment