How Often Should Transformer Oil Be Tested?

The transformer oil testing cycle you're concerned about is indeed related to the long-term stable operation of the equipment. The testing cycle varies significantly depending on the type of equipment, voltage level, and operating conditions, and cannot be applied uniformly. The following is a detailed explanation based on comprehensive power industry standards and practical operation and maintenance experience:

Routine Inspection Cycle: Classified by voltage level and equipment type

220kV and above ultra-high voltage transformers

Dissolved gas analysis (DGA): Every 6 months

Routine oil quality testing (breakdown voltage, acid value, moisture, etc.): At least twice a year

Particle size testing: Every 3 years during operation, or additional testing when oil dielectric loss is abnormal

110kV and below transformers

DGA testing: Once a year

Routine testing: At least once a year

35kV and above distribution transformers (8MVA and above)

Oil sample testing cycle: Once a year

6~10kV distribution transformers

Belonging to secondary equipment, the routine oil sample testing cycle is generally once every 3 years. Withstand voltage testing can be performed annually.

100kVA and above service transformers, station service transformers