How to check transformer fault?

Usually the transformer fault can be checked from the following aspects:
(1) Appearance inspection: no abnormal sound, smell; Whether the temperature indication value exceeds the specified oil pillow oil level is normal:

Whether there is oil leakage outside the box;

Whether the explosion-proof film is broken;

Whether the high and low voltage lead joints are discolored due to overheating;

Whether the insulated porcelain tube is in good condition.

(2) For the small power transformer should check whether the fuse meets the specified specifications; No local damage or poor contact,

(3) Check whether the relay protection is operated or tripped according to the specified current and time.

(4) Check whether there is gas in the gas relay. If there is gas, the fault and production site should be analyzed in terms of color, odor and chemical composition