Maintenance Of Cast Resin Transformers

I. Maintainance

If a cast resin transformer is operated under general rated conditions described in specifications; a one-year period is enough to inspect.

However, in case of a special place where the air is contaminated by particles such as dust or chemicals, inspect the transformer every 3 months or even more frequently.

1. Inspection

Transformers need to be maintained periodically to ensure stable operation. Inspections should be taken when necessary. There are two types of inspections as follows:

1.1 Routine Inspection:

The checklist is as follows:

Check temperature and humidity

Check load conditions (Voltage, Current, kW, etc.)

Check for abnormal noise, smell, and evidence of Overheating

1.2 Periodical Inspection

The period of these checks will be depending on the environment where this transformer is installed.

Dust and dirt on the winding and in the cooling, the duct should be removed to avoid hindering the cooling and weakening the insulation.

Check electrical insulation with megger

Check every connection

Check the tightness of the tap changer

It is necessary to remove the accumulation of dirt on the windings or insulators to permit free circulation of air and to protect against the possibility of insulation failure.

Some steps to clean a cast resin transformer

• Shut off the power of a cast resin transformer according to safety rules.
• Open a door of housing for handling high voltage windings of a cast resin transformer.
• Wipe all iron cores of a cast resin transformer. At this time, be careful not to be wounded by sharp parts or projecting parts. If possible, use a vacuum cleaner to get rid of dust or small fragments.
• Wipe dust or small fragments out which are adhered to a coil, a frame, a cable, a busbar, an insulator, and other surfaces within the housing. Wipe them out using a vacuum cleaner or a rag.
• Clean a coil with a damp rag. Germicidal alcohol can be used. However, don't drench a rag with alcohol. Dry coils after cleaning.
• After cleaning is finished, remove all rags and tools for maintenance from coils. Check again whether there is an alien substance in the upper parts, lower parts, and inner parts of a cast resin transformer.