1. Inspection of transformer appearance and turn ratio by turn ratio tester.
1) Check whether the transformer oil level indicator on oil conservator is in good condition by transformer oil tester, whether the oil level is clear and on the oil level line conforming to the ambient environment and should not higher or lower. If level is higher, the oil temperature will rise and oil expansion will be caused after the transformer runs with load. Besides, the oil might be overflowed from respirator communicating pipe on the top of oil conservator; if oil level lower, the oil level might go down to the invisible location on the oil level indicator when the transformer runs with light load or within short time in winter.
2) Check whether the sealing of the cover plate, sleeve, oil level indicator and vent valve is good and there is no phenomenon of oil leakage. Otherwise, after the transformer runs with load, the more severe leakage phenomenon might be caused under heat condition.
3) Check whether the explosion-proof membrane of explosion stack (explosion-proof tube) is in good condition.
4) Check whether the moisture absorption agent of respirator loses efficacy. checking turn ratio by turn ratio tester.
5. Check whether the earthing of shell of transfer by transformer instrument is firm and reliable for it plays a direct role in protecting transformer.
6) Check whether primary and secondary outlet sleeves of transformer and their connection with the guide line is good and whether the phase color is correct.
7) Check whether the name plate on the transformer conforms to the specification of transformer selected according to the requirement, like side voltage grade, wiring group of transformer, capacity of transformer and tap switch location, etc. All above items will be checked by transformer instrument accordingly.