Shaanxi Hanzhong Transformer Co., ltd

After vacuum oiling of transformers of 220kV and above voltage level, hot oil circulation must be carried out. Circulation time: 220~330kV transformer shall not be less than 24 hours; 500kV transformer shall not be less than 48 hours.



Transformer oiling before body heating hot oil circulation.

Process flow chart

sxhztransformer-20220620-15.jpg


Method steps.


1、connect the oil storage tank, oil filter, transformer oil pipeline. Transformer oil injection should be injected from the top valve of the body.


2、Connect transformer, vacuum pump evacuation pipeline.


3、After the transformer is checked and sealed, start the vacuum pump to draw vacuum.


4, before oil injection, test transformer oil samples to meet the oil injection and nitrogen discharge oil quality requirements can be. Transformer final oil level should be higher than 100mm above the upper edge of the core.


5、The oil temperature of the oil filter outlet should be between 50~70℃. Connect the oil filter inlet pipe to the valve at the bottom of the transformer. Start the oil filter machine, first open the oil filter machine side oil inlet valve, use the oil filter machine vacuum pump to empty the air in the oil inlet pipe, then open the transformer bottom valve, transformer cycle heating, transformer body temperature exceeds 20 ℃ can stop the cycle heating.


6、Inject dry air into the transformer through the valve at the top of the body when releasing oil to prevent moisture from entering.


Cautions.


1、Transformer oil should be taken before injecting into the internal body of the transformer oil sample test, to meet the oil quality standards before oil injection.


2、 oil injection should be injected from the top of the transformer.


3、 hot oil circulation process should prevent moisture gas or impurities into the transformer interior.


The transformer oil vacuum oil injection after hot oil circulation


Process flow chart.


sxhztransformer-20220620-16.jpg

Method steps


1、Transformer vacuum oil injection to 200mm from the top cover of the body, for hot oil circulation, to continue to maintain vacuum, vacuum should meet the requirements of the regulations.


2、Under the transformer keep vacuum, connect the oil circulation pipeline. The oil filter inlet pipeline is connected to the valve at the bottom of the transformer, and the oil filter outlet pipeline is connected to the oil injection valve at the top of the transformer body.


3、Start the oil filter vacuum pump, open the oil filter inlet valve, open the transformer bottom valve after vacuuming the oil filter inlet pipe, make the oil filter inlet, and carry out self-circulation heating of warm oil. Open the oil injection valve at the top of the transformer, so that the air in the oil injection tube is discharged through the vacuum pump. Open the oil filter outlet valve for hot oil circulation heating.


4、Transformer vacuum oil injection to the oil storage cabinet after the specified oil level of the full oil state for hot oil circulation, the transformer does not draw vacuum. The oil filter inlet pipeline is handled as above. When the oil filter outlet pipeline is connected, the oil injection valve at the top of the transformer body has a bleeder plug, so use the bleeder plug to discharge the gas in the pipeline to make the oil pipeline full of oil and then open the valve at the top of the body to heat the hot oil cycle.


5、 full oil state before the hot oil cycle, check the moisture absorber has been correctly installed, breathing smoothly.


6、When the hot oil circulates, the oil temperature at the outlet of the oil filter should not be lower than 50℃, and the temperature inside the oil tank should not be lower than 40℃.


7、Transformer that keeps vacuum during hot oil circulation, the oil replenishment order is the same order as oil replenishment by vacuum injection.


8, after the hot oil cycle oil sampling test, should reach the current national standard "electrical installation engineering electrical equipment handover test standards" provisions.


9, the transformer hot oil cycle is completed, after the completion of oil injection, before applying voltage, should be left to stand for a period of time. Resting time should not be less than the following provisions.


110KV and below 24h
220KV and 330KV 48h
500KV 72h


10、After the transformer has been resting, it should be deflated several times from the transformer's casing, elevated seat, cooling device, gas relay and pressure release device and other related parts, and the submerged oil pump should be started until the residual gas is exhausted.


11、The exhaust in the oil storage cabinet must be carried out according to the manufacturer's regulations.


Cautions


1、Transformers of 220kV and above voltage level must be circulated with hot oil.


2、The oil level specified in the oil storage cabinet should be slightly higher than the corresponding temperature position according to the oil level temperature curve when filling oil.


3、The pipeline before the hot oil circulation is connected, to exclude the gas in the pipeline. Transformer oiling pipeline can use the body valve exhaust plug exhaust. If the body valve without exhaust plug, can be installed in the front of the oil injection pipe valve, the oil injection pipe will be filled with oil, with the addition of the valve and the body valve connection.


4、The oil in the cooler should be circulated with the oil in the main body of the tank for hot oil at the same time, and the submersible oil pump and the valve can be closed intermittently in order to maintain the temperature of the oil tank.


5、Full oil state for hot oil circulation before must check moisture absorber breathe smoothly, oil seal oil level is normal.


6、After the transformer is resting, all the bleeding plugs should be deflated for several times. Cooling device with submersible oil pump, should start the submersible oil pump for several times static deflation. Oil storage cabinet according to the manufacturer's regulations in order to exhaust.


Third, the transformer hot oil cycle to complete the standard.


1、Hot oil circulation should be carried out in the full oil state after vacuum oil injection to the rated oil level of the oil storage cabinet.


2、Oil filter outlet oil temperature is not less than 50℃, the temperature in the oil tank is not less than 40℃.


3、After oil injection, the transformer resting time should meet the requirements.


4、Transformer by several exhaust, residual gas exhausted.


5、Transformer oil sample inspection to meet the current national standards "electrical installation project electrical equipment handover test standards" provisions.


6、Transformer sealing is good, no seepage dew.


7, transformer oil storage cabinet oil level in the specified oil level.


8、moisture absorber silica gel color is normal, breathing usually.

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