To assess whether oil replacement is required for an oil-immersed transformer, the following maintenance checks should be performed regularly:

​Temperature Monitoring​
During operation, the transformer’s temperature will naturally rise, but it must remain within a safe range (typically not exceeding 85°C). If the temperature exceeds this threshold, first check if the transformer is overloaded. If overloading is confirmed, reduce the load; meanwhile, enhance natural ventilation in the equipment room to dissipate heat.

​Oil Quality Inspection​
The primary focus here is to detect impurities, residues, or sediment in the transformer oil, as these contaminants can degrade oil performance and compromise its effectiveness. To ensure the oil fully fulfills its roles (e.g., insulation, cooling), we recommend conducting periodic checks on three key parameters: oil volume, temperature, and quality. Any issues identified should be addressed promptly and targeted.

​Oil Level Check​
The oil level directly reflects the remaining quantity of transformer oil. A low oil level can impair the transformer’s operational characteristics and increase overall energy losses, posing significant risks to its performance and longevity.

​Key Notes:​​

· Oil replacement is not arbitrarily frequent but determined by maintenance needs and oil condition.

· Regular inspections (temperature, quality, and level) are critical to proactive maintenance and preventing potential failures.