What You Need to Know About Transformer Maintenance

Power transformers are one of the most important and expensive components of an electrical system. For this reason, regular maintenance and inspections are necessary to achieve optimal performance and a longer service life.

If maintenance checks are performed routinely, major breakdown maintenance may not be required. This helps reduce downtime and saves operational costs. In addition, when a transformer fails, it may suffer irreversible damage or create risks such as explosion or fire, which can harm the environment.

Especially in critical facilities such as factories, energy plants, petrochemical installations, and mining facilities, regular transformer maintenance is a mandatory requirement.

Monthly Maintenance Checks

• The oil level in the tank must be checked monthly to ensure it does not fall below the minimum level and cause damage.
• Breather openings must be kept clean to ensure proper air circulation.
• If the transformer has an oil filling bushing, monthly checks are required to ensure the oil level is correct.

Daily Basic Maintenance Checks

Two basic maintenance tasks should be performed daily:

• The oil level indicators of the main tank and conservator tank should always be maintained at the required level.
• Any oil leakage should be immediately reported to technical specialists.

Annual Maintenance Program

• Cooling equipment such as air fans, oil pumps, and other auxiliary components must be inspected annually.
• All transformer surfaces should be cleaned once a year using a soft cotton cloth.
• The oil condition must be tested annually by taking samples from the drain valve and analyzing moisture content (PPM) and dielectric strength (BDV). If BDV is low and PPM is high, the oil must be replaced.
• The condition of transformer windings must be checked. Both resistance and insulation resistance of primary and secondary windings must be measured.
• The transformation ratio of windings must be checked, especially in parallel systems. Tap changer connections must be verified.
• All control panels and marshalling boxes must be cleaned annually. Heating and lighting systems must be checked. Terminal connections of control and relay cables must be tightened at least once a year.
• Control switches, alarms, relays, remote tap changer systems, and control panels must be cleaned with appropriate cleaning agents.
• In high-power transformers, tap changer contact oil must be replaced due to arc effects during switching operations.

• Protection systems such as differential relays, Buchholz relay, temperature relay, reverse power relay, earth fault relay, short circuit protection relay, and overcurrent relay must be checked for proper operation.
• Oil levels for winding temperature and oil temperature indicators must be checked and refilled if necessary.
• Moisture is one of the biggest threats to transformers; silica gel used for moisture control must be inspected.
• Grounding resistance must be measured.
• Porcelain bushings must be carefully cleaned using a cotton cloth.

Final Notes

Transformer maintenance is not limited to the points mentioned above. Each transformer may require specific maintenance depending on its structure and operating conditions. Therefore, inspection by expert field teams is essential.

Maintenance must be performed regularly and systematically by facility maintenance teams. Otherwise, serious risks such as loss of life, property damage, production losses, or irreversible transformer failures may occur.