Power & Distribution Transformers

The Value of Diagnostic Testing

Power transformers are among the most strategically important and expensive components on any network. Data on their health is therefore vital for effective asset management. Recent advances in techniques for measuring and analysing the condition of transformers have made diagnostic testing more cost effective and valuable than ever.

When to Test Transformers

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  • Whenever a new transformer is commissioned
  • Routinely during their lifetime, to monitor changes in condition
  • Following repairs
  • To diagnose faults


Benefits of Transformer Testing

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  • Develop Health Indices to estimate End of Life
  • Check condition following fault conditions or overloading
  • Extend transformer life
  • Maintain high utilization of existing transformers
  • Improve loading capabilities
  • Identify transformers at risk of failure
  • Prevent expensive and disruptive failures
  • Minimize replacement costs
  • Improve decision making for future load requirements
  • Improve safety


AMEC’s skilled testing engineers are equipped with the latest electrical testing equipments and can provide on site testing of your transformers. We specialize in the following transformer tests:

SFRA – Sweep Frequency Response Analysis

The SFRA test is suitable for power transformers and can detect various faults including shorted turns or open winding, axial deformation, partial winding collapse, hoop buckling, broken or loose clamping structures for winding/core etc. AMEC provides sweep frequency testing as one of the many diagnostic tests to help determine the health and condition of your transformer.

Tan Delta & Capacitance Measurement for Windings and Bushings

Power factor testing of electrical insulation is one of the most recognized and highly regarded procedures in both preventive maintenance process and manufacturing of electrical power apparatus such as transformers, reactors,cables, electromechanical rotating machines etc.

Tan Delta & Resistivity Testing for Transformer Oil

Electrical properties of the insulating system change over time. The principal contributor to the unexpected breakdown of the high voltage equipment is insulation failure. By measuring the electrical properties of oil, it is possible to ensure the operational unexpected breakdown. Tan-Delta is one of the most powerful diagnostic tool to monitor the condition of insulating medium of various HV equipment.

Acceptance Testing

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  • Turns ratio / voltage ratio
  • Winding resistance
  • Calibration of oil/ winding temperature indicators
  • Insulation resistance
  • Vector group and polarity check
  • DC resistance measurement,
  • Primary Injection test
  • Zero sequence measurements
  • Load loss & impedance measurement test
  • No load loss & magnetizing current measurement test
  • High voltage test both HV & LV
  • Induce over voltage test double voltage,double frequency


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