How to Maintain Dry Type Electrical Transformer


Dry type transformers require regular maintenance and repairs to ensure that they last for long. Regular servicing and inspection of dry type electrical transformers will bring to notice any faults or issues that may go unnoticed while the transformer is running. Even though you might call the professional for fixing any problems that arise, it is a good practice to conduct regular checkups for ensuring the safety and maintenance of the transformer.

Electrical transformers require inspection every three to six months. The formation of dust and subtle issues may only be visible with regular monitoring. The dirt particles also hinder the airflow, which might lead to a dusty smell in the area. The periodic maintenance of the transformer depends on the operating conditions and the load that is applicable to it.

In this article, we will look at a few things important for the maintenance of dry type electrical transformers. If the transformer is in a clean space, an annual maintenance check is okay. However, for transformers that are installed in spaces where dust and dirt can accumulate, regular checkups are important. Let’s have a look at the guide in detail.

Checklist for Maintaining Dry Type Electrical Transformers

There are multiple types of inspection to check the transformer for any issues or dust accumulation. Maintaining the transformer is challenging – therefore, you need to hire a professional company that works with electrical transformers. Here’s what you need to consider for the proper maintenance of the dry transformer

Dust inspection

The first step is to check for any dust accumulation on the louver, screen, or internal cooling coil. If there’s any dust, then wait till the transformer is de-energized. After that, vacuum out as much dust as possible. Using a brush to clean the lint screen is a good option. Do not use soap or any detergent to wash the transformer. Use a blow dryer for inaccessible areas.

When transformer is energized

At this stage, inspect that the ventilation is working properly or not. This is the right phase to check the sound the transformer makes. If there are any unusual sounds, it is good to call a professional who can look at the transformer and solve the issue. The sound may arise due to accumulated dirt and debris of the building, which must be cleaned as soon as possible.

Check for internal defects

Cleaning of the transformer requires a careful look at the clamps and core steel for any signs of rusting. The insulation and surfaces must be checked for discolouration. If they are discoloured, it means there is overheating and a connection might be loose somewhere. A professional is required to evaluate the entire internal components and tighten the wiring and connections to ensure proper hardware usage.

Routine tests

Maintenance of dry type transformers involves routine tests and checkups. There are two tests that can be executed for inspecting the performance. Transformer Turns Ratio test is done when there is discolouration or you may think that there is any electrical issue with the system. The Dielectric Absorption test is conducted from windings to windings and then windings to the ground. It’s polarization index value should be greater than 2.0 for smooth performance.


Never wait for the transformer to start showing signs of problems. Take preventive measures to ensure that the electrical transformers don’t stop working. Conduct regular inspection for dust and dirt particles, check for discolouration, tighten the hardware, and re-energize the system to conduct tests. Always hire a professional who can check the transformer and ensure that everything is working perfectly. It will save you a lot of time and money, along with reducing the risk of any damage that may occur.

If you want to know more about dry type transformer maintenance, click here.