Changes of Oil-immersed transformers
Recommendation of preventive maintenance
After years of operation, an oil-immersed transformer reaches its end of life. The failure rate of oil-immersed transformers tend to become high after 15 years of operation. Even though the appearance is fairly good, there are possibilities of dangerous conditions.
Benefits of preventive maintenance
- Preventive Maintenance means “preventive action against failure occurrence” and is abbreviated as PM.
It is a particularly important type of maintenance.
- This “preventive maintenance” exerts its power effectively during the “wear-out failure period” in the bathtub curve.
What you can expect from PM:
– Accident prevention – Prevention of aging degradation – Extension of life span
Recommended replacement time of parts
Japan Electrical Manufacturers’ Association (JEMA) and Electric Technology Research Association recommend accessories/parts replacement to prolong transformer life. Please study it in conjunction with your plan of transformer inspection.
|Accessory name||Recommended replacement time||Requirement of power-off|
|Dial thermometer||Every 10 years||Yes|
|Pressure gauge||Every 15 years||Yes|
|Oil gauge||Every 15 years||Yes|
|Pressure release plate||Every 15 years||Yes|
|Bushing||Every 15 years||Yes|
|All sorts of gaskets||Every 10 to 15 years||Yes|