How to Clean Your Dry-Type Transformer

Over time, dirt and dust can accumulate inside your dry-type transformer. Periodically removing this dirt is necessary to keep your transformers running properly. If left unchecked, this buildup can:

• Restrict airflow
• Raise operating temperatures
• Increase the risk of insulation failure.

A routine cleaning and inspection schedule is one of the simplest ways to extend the life of your transformer.

Dry-Type Inspection and Cleaning Guidelines

Regularly inspect your transformer for any signs of dust or debris build-up. Inspections, at least once a year, will ensure your transformer doesn’t suffer from overheating, arcing or over-voltage creep. 

Always ensure the transformer is deenergized before inspection or cleaning the unit.

During the inspection, pay close attention to:

• Live bus, tap leads, and connection points: These exposed, non-insulated areas commonly collect debris.
• Top and bottom of winding assemblies: Settled dust often hides in ledges in the coil.
• Enclosure Vents: Blockages here directly impact cooling performance.

If you see tracking or carbonization on the insulating surface, this is a sign that your transformer may already be compromised. This looks like black burn marks on the insulation.

If you see burn marks, immediately remove the unit from service. It should be inspected and tested before it is used again. It may need to be repaired or replaced. 

How to Clean Transformer Windings

For a light cleaning, you can use a vacuum or compressed air to clear your transformer's windings of debris. Or, use both: 

1. Vacuum Cleaning

First use a vacuum to remove loose dust from coil surfaces and crevices.

2. Low-Pressure Compressed Air

After vacuuming, a second pass with compressed air helps loosen any particles the vacuum didn’t reach.

• Keep air pressure below 25 PSI to avoid damaging insulation or shifting conductors.
  

These two steps together provide a thorough dry cleaning without risking moisture intrusion.

Cleaning Insulating Surfaces and Connections

For components such as jumper leads, voltage adjustment taps, and various connection points:

• Use a dry, lint-free, non-abrasive cloth to wipe away any dust or debris.‍
• Avoid liquid cleaners entirely. Many solvents and detergents can degrade insulation materials or leave conductive residue.

Cleaning the Vent Filters

Some larger dry-type substations have removable vent filters to help maintain clean airflow. These filters should also be inspected and cleaned regularly.

To clean these filters:

1. Remove the steel filter cover by loosening the retaining screws.
2. Pull the filter out using the provided tabs.
3. Wash the filter with mild soap and water.
4. Allow it to dry completely before reinstalling.

How often should you clean your transformer?

If the transformer is installed in a relatively dust-free environment, an annual cleaning is enough. In a dusty environment, more frequent cleaning and inspection may be necessary.

For thorough repairs and inspection, send your transformer to Maddox. We can also bake out the core and coil if the moisture is too high. We’re equipped to perform all testing, repairs, and remanufacturing necessary to keep your transformer running well. If you’ve got more questions about maintaining your transformer, reach out to us today!