Your Perfect Guide for Dry Type Transformers Maintenance

Dry-Type Transformers Manufacturer

Tips to Improve the Performance of Dry-Type Transformers

Transformers are the lifeline of your business as they regulate the right flow of electricity by either stepping up or stepping down the power as required. Failure of your transformer would lead to losses in production and eventually eat into your profits. Therefore, you need to pay attention to dry-type transformer maintenance regularly.

Checklist for maintaining dry-type electrical transformers:

Dry-type electrical transformers don’t use insulating liquid but air to cool the system. Problems with dry-type transformers occur when there is moisture in the windings. Moisture accumulates when they are kept in or de-energized in areas with high levels of humidity, dampness or extreme fluctuations in temperature.

There should be a routine inspection and maintenance schedule to ensure the smooth functioning of your transformer. The operating environment and the applied load have a bearing on the maintenance required.

There are some precautions to be kept in mind before undertaking the transformer maintenance. The transformer should be de-energized before maintenance, and the transformer terminals should be connected to the ground. These connections should be removed before re-energizing the transformer.

To keep the dry-type electrical transformers in proper working condition, the following checks need to be undertaken:

Evidence of rusting or corrosion

There should be regular inspection of dry-type electrical transformers for rusting, corrosion, insulation, paint or varnish. The insulation should be checked for wear and tear. You need to take immediate corrective measures. There should be inspection and servicing of auxiliary devices as well.


Check for contaminants either on the insulation of the windings or where air flow could be restricted. Loose connections, tap changer condition, terminal boards and the general state of the transformer need to be inspected. Evidence of overheating and carbonization also marks merit inspection.

Windings or insulators should be kept dust-free to permit sufficient circulation of air and prevent the breakdown of insulation. The vents should be cleaned appropriately.

A vacuum cleaner, compressed air or a blower can be used for cleaning the windings. Ensure sufficient ventilation while cleaning.

Use a brush or a dry lint-free cloth to clean the lead supports, terminal boards and tap changers, bushings and other vital insulating surfaces. Avoid using liquid cleaners as this could lead to accumulation of dust and adversely affect the transformer. Dust and debris are the primary reasons for overheating of the transformer and electrically short.

Insulation resistance test

This test will determine the moisture content of the insulation material in the transformer- Transformers which are over 500 kVA with primary voltage more than 600V malfunction due to moisture.

Both the primary and secondary windings should be examined for resistance between them and between individual windings and ground. The results need to be checked with the minimum insurance resistance table.

Applied Voltage Test

After the insulation resistance test, you need to conduct the applied voltage test.

The difference between the test voltage and the rated winding voltage should not be more than 1 kV or the limit specified by the dry-type transformer manufacturer. The minimum resistance readings should match the manufacturer recommendations before the transformer is energized. The ambient temperature influences the recommended temperature readings.

The presence of moisture is indicated for resistance readings less than 20,000 ohms per volt. This testing can be done using a high potential or hi-pot tester.

The manufacturer’s recommendation should be followed while drying out the transformer.

De-energized state

When the transformer is de-energized, there are certain checks required. All the available hardware need to be tightened, cooling fans cleaned, insulation surfaces inspected for discoloration or heat damage and isolation dampeners for deterioration.

Energized state

When the transformer is energized, it is crucial to ensure adequate ventilation. The audible sounds that are emitted by the transformer should be monitored for any noticeable changes.

Dry-type transformers need regular monitoring for any signs of deterioration or performance.

Get the Best from Your Dry-Type Transformer

To maximize the potential of your transformer, ensure that you purchase it from a reliable manufacturer with extensive experience as well as compliance with engineering standards. Electric Power Inc is a trustworthy dry-type transformer manufacturer in the Mississauga area, and they can be contacted for your requirements.