1、Before transformer evacuation and oil injection, we must check and confirm that the internal work of transformer body is finished, and the internal cleaning of the body is clean without any leftovers. Check and confirm that the overall installation of the transformer is completed. Check and confirm that the transformer and the relevant piping system are well sealed.

2、Before vacuum oil injection, oil samples must be taken for inspection, and oil can be injected only after passing inspection.

3、According to the transformer manufacturer's regulations, the oil tank and accessories that need to be vacuumed and oiled must be connected with pipeline, and vacuumed and oiled at the same time. The pipeline connection of the oil chamber of the on-load switch should be made according to the requirements of the switch instruction manual.

4、Before vacuum oiling, the temperature of transformer body is less than 20℃, it should be heated by hot oil circulation. The hot oil should be injected into the oil tank from the top of the transformer. Oil injection before the radiator and transformer connected to all the valves closed, the radiator is not filled with oil to prevent the oil temperature cooling lower. Oil injection to the oil surface more than 100mm along the core can be.

5、For the transformer of 110kV voltage level, if the capacity is larger and it is inflatable for transportation, the oil should be pumped and injected.

6、The limit allowable value of transformer evacuation should be based on the value specified by transformer manufacturer, and the vacuum degree in table 2.5.3 is used if the transformer manufacturer has no clear regulation.

7、The transformer must check the state of oil tank and valve before vacuuming. The parts which are not allowed to draw vacuum must be isolated, and the parts which are allowed to draw the same vacuum should be drawn at the same time. The water cooler should be carried out according to the operation manual.

8、The outlet of vacuum pump should be with solenoid valve, if there is no solenoid valve, the valve should be installed, and the vacuum pump can be stopped only after the valve is closed in the pumping process.

9、When using the mercury vacuum meter, the position of the mercury vacuum meter should be lower than the position of the transformer vacuum valve. A small valve should be installed at the front of the pipeline of mercury vacuum meter, and the valve should be closed when not in use. Use the mercury vacuum meter correctly according to the instruction of mercury vacuum meter.

10、Check whether there is leakage at each seal in the process of pumping vacuum. Check the leakage location method: listen to the joint in detail whether there is a squeaking air inlet sound, there is a sound that the leakage site; ignite the mosquito incense, make the smoke move along the installation of the suspicious parts, check the upper part of the plate to block the smoke, so that the smoke does not leave the inspection site, found that the smoke is sucked inward tilt, this location is the leakage site (please pay attention to fire prevention when using this method). After the transformer vacuum reaches the specified value, close the transformer body vacuum valve, stop the vacuum pump running, record the vacuum value with mercury vacuum meter every 5 minutes for 30 minutes, and the vacuum drops not more than 15Pa in 30 minutes, which can be considered that the transformer is well sealed.

11、Oil storage cabinet for vacuum injection, oil replenishment, exhaust must be carried out in the order specified by the manufacturer.