Laxmi Associates

Laxmi logo

Transformer Tests Their Purpose and Importance: Know All About


A transformer is an easy-to-use gadget. It is the main element for high voltage power transmission. You will find various kinds of transformers, used for many different purposes in the electrical system. 

Transformer Tests Their Purpose and Importance

Types of Transformers : 

Single-phase Transformer 

  • This transformer receives electrical power from a single-phase source.
  • Delivers power to single-phase load

Three-phase Transformer 

  • This type of transformer consists of three sets of primary and secondary windings.
  • It has delta or star-shaped windings.  

 Instrument Transformer

  • An instrument transformer is used for measuring and instrumentation objectives.
  • Two types of instrument transformer: a)Current transformer is used to measure electric current flow in a circuit. (b)A Potential Transformer is used to measure the voltage.

Distribution Transformer 

  • This transformer is used to step down the voltage level for distributing the electricity in the local area.
  • It is usually seen in buildings, societies, and housings.

Power Transformer 

  • The power transformer is used to transmit electric power in a high voltage circuit
  • The design of the power transformer is designed such that it handles higher power.

Testing of Transformer 

Transformers have to be tested to check their functioning and to maintain their working capacity and lower the chances of failure if any. Below listed are the types of testing of transformers:

  1. Resistance test 
  2. Insulation resistance test 
  3. Power factor test 
  4. Turns ratio test

1. What is a Resistance test?

  • The resistance test of a transformer is conducted using an ohmmeter.
  • Leave the transformer to settle at the same temperature as the atmosphere surrounding it.
  • With this test, one can check for any differences in the openings and the windings of the transformers 
  • After this test, one can confirm that all the open transformers are correctly wired and connected correctly. 

2. What is an insulation test/ Megger test?

  • Also known as the Megger test
  • The insulation test of a transformer is conducted using a megohmmeter.
  •  It is used to determine the quality of the insulation 
  • If the insulation works appropriately, it will show greater resistance 
  • Note that if it shows any lower resistance, then it is a sign of an issue.

3. What is a Power Factor test?

  • The power factor test of a transformer in which the power loss can be identified by measuring the angle.
  • For an accurate result, the angle of the currents should ideally be 90 degrees.
  • By this test, you can determine any decrease or any malfunction of the insulation.
  • This test can be completed with a power factor test kit.

4. What is a Turns Ratio test?

  • This is an AC low voltage test to determine the ratio of high voltage winding. 
  • The Turns Ratio test of a transformer is conducted using a Transformer Turns Ratio tester.
  • Through this test, one will know about the transformer, whether it will provide a step up or a step-down voltage. 
  • This test is conducted on all taps of every winding of the transformer.

Importance And Purpose of Transformer Testing 

Transformers play an important role in generating electricity, transmitting power, distribution, and utilization of electricity. So regular testing and maintenance of transformers are evident. Below listed are some of the primary reasons for transformers testing:

  • To check if the main parts/components of electrical transformers are working correctly.
  • To check the functioning of the whole transformer.
  • To reduce the risk of failure of working. 
  • To confirm the specifications and performance of the transformer.
  • To avoid future failure risks that happen because of electrical, thermal, or mechanical issues. 

These were some common uses of transformers, types, and various tests of transformers and their importance. I hope this article had all the answers you were looking for. Keep coming back to Laxmi Associates’ website for anything and everything related to electrical engineering consultancy and solutions.