油浸式变压器一般在投入运行后5年内和以后每间隔10年大修再一次。箱沿焊接的全密封油浸式变压器或制造厂另有规定者，若经过试验与检查并结合运行情况，判定有内部故障或本体严重渗漏时，才进行大修。
Oil-immersed transformers are usually overhauled again within 5 years after operation and every 10 years after operation. Fully sealed oil-immersed transformer or manufacturer with welded edge of box has other requirements. If the internal fault or serious leakage of the main body is determined by test and inspection combined with operation conditions, the overhaul will be carried out.
在电力系统中运行的主油浸式变压器当承受出口短路后，经综合诊断分析，可考虑提前大修。运行中的油浸式变压器，当发现异常状况或经试验判明有内部故障时，应提前进行大修;运行正常的油浸式变压器经综合诊断分析良好，经总工程师批准，可适当延长大修周期。
When the main oil-immersed transformer operates in the power system withstands short circuit at the outlet, it can be considered to overhaul ahead of schedule after comprehensive diagnosis and analysis. Oil-immersed transformers in operation should be overhauled in advance when abnormal conditions are found or internal faults are identified by tests. Oil-immersed transformers in normal operation are well diagnosed and analyzed by comprehensive diagnosis, and the overhaul period can be prolonged appropriately with the approval of chief engineer.