Shaanxi Hanzhong Transformer Co., ltd

Transformer oil drain, gas replacement preparation

1. When the transformer arrives at the site and cannot be installed within three months, the following work should be carried out within one month.


Transformer transported with oil.


Check the oil tank seal should be good, no leakage.


Measure the insulation strength of the oil inside the china power transformer.


Measure the insulation resistance of the windings (transformers that are transported without bushings may not be measured).


Install oil storage cabinet and moisture absorber, inject qualified oil to the specified oil level of oil storage cabinet, or in the case of no oil storage cabinet, after the upper part is evacuated, fill with 0.01~0.03MPa nitrogen, with nitrogen purity not less than 99.9% and dew point lower than -40℃. During the oil-filled storage period, it should be checked frequently for oil seepage and rusting of equipment appearance, and the insulation strength of oil should be checked once every six months. The gas pressure should be checked daily during gas-filled storage, and records should be kept.


Gas-filled transportation of transformers.


Oil storage cabinet and moisture absorber should be installed, inject qualified oil to the specified oil level of the storage cabinet. Check the transformer body gas pressure should be normal before installation.


If the oil cannot be injected in time, it should continue to be filled with the same gas as the original gas for safekeeping. The transformer must be equipped with pressure monitoring device, the force should be maintained as 0.01~0.03MPa, and the gas dew point should be lower than -40℃. The oil-filled storage period should be checked frequently for oil seepage and rusting of equipment appearance, and the insulation strength of oil should be checked once every six months. The gas pressure should be checked daily during gas-filled storage, and records should be made.


After the transformer arrives at the site, according to the manufacturer's regulations, the transportation process and the transformer installation regulations, the installation technician and the transformer manufacturer's personnel, Party A and the supervisor jointly determine whether the transformer needs body inspection. If the body check, determine the hanging cover or hanging body, or not hanging cover directly into the oil tank to check.


2、After the transformer arrives at the site, make oil pipeline connections and vacuum pipeline system connections according to the actual size of the transformer body valves and flanges.


3、Transformer oil drain and gas replacement before consulting local meteorological department, choose a good climate date to work.


Transformer oil discharge, gas replacement method steps


1、Oil-filled and preserved transformer oil discharge.


Check the transformer, oil filter, oil tank, oil pipeline grounding should be solid and reliable.


Oil samples should be taken before releasing oil, measuring the insulation strength and water content of transformer oil, to confirm that the transformer is not damp.


Transformer around the air temperature is lower than 0 ℃, should use hot oil circulation heating transformer body heating, so that the body temperature is higher than the surrounding air temperature 15 ℃.


Make preparations for transformer vacuum pump, vacuum piping and mercury vacuum gauge connection.


Transformer oil should be put into a sealed and clean special oil tank, transformer oil should be injected into the tank from the valve at the bottom of the tank.


Measure the relative humidity of air when discharging oil, and record the start time of oil discharge.


Oil discharge should reduce the exposed area of transformer body, and dry air should be injected into the transformer body.


2、Gas replacement.


① Long-term gas transportation and on-site storage of the transformer, the transformer body should be used for gas replacement by oil injection.


Before oil injection, transformer oil must be filtered by oil treatment, sampling test meet the requirements before injection into the transformer.


Before oil injection, the residual oil in the oil tank should be drained.


The transformer oil should be injected into the transformer from the lower valve of the transformer through the high vacuum oil filter, and the gas should be discharged from the top of the transformer. Open the top cover of the transformer first, and then carry out oil injection.


Transformer oil should be injected to the top of the oil tank to exhaust the gas in the oil tank, and the final oil level should be more than 100mm above the top edge of the core.


After the transformer oil tank is filled to the final oil level, record the time. The resting time of the oil in the transformer tank should be not less than 12 hours.


② Short time nitrogen filled transport to the site, immediately ready to install the transformer, can be used to evacuate nitrogen by vacuum.


Connect the vacuum pipeline, the vacuum pump should be installed in the air circulation.


When breaking the vacuum of transformer, dry air should be injected to avoid the entry of humid air.


When the oxygen content in the body does not exceed 19%, the staff shall not enter the transformer body.


③Nitrogen-filled transport preservation transformer need to hang cover check, must let the body in the air exposure for more than 15 minutes, to be nitrogen diffusion after the body check.

 

Transformer oil release, gas replacement precautions


1, the transformer body in place, to first do a good job transformer grounding, to ensure that the transformer body has two points and the main grounding network connected to different points. For the upper and lower section of the oil tank with bolts connected to the transformer, to connect the upper and lower tank short wiring.


2, oil-filled custody of the transformer, the top of the tank oil is not all full, sealing is not good to check, only check the top of the tank each bolt should be fastened well.


3, inflatable custody of the transformer, to check the gas pressure every day, make a record. Compare the pressure records, if the pressure drops abnormally, should check whether there is leakage in the body of the apparatus, timely replenishment of the same gas as the original filling gas, keep 0.01~0.03MPa positive pressure.


4、Oil pipeline and evacuation pipeline should use reinforced PVC pipe, should not use rubber pipe.


5、Open the top cover of the transformer for gas storage first, there is gas escaping before oil filling.


6、Transformer oil release and gas replacement should not be carried out on rainy, snowy or foggy days. To prevent the dust from flying, the transformer can be


To prevent dust from flying, water or plastic sheeting can be used to cover the site around the transformer construction area.


7、Transformer oil drain and gas replacement process should measure and record the relative humidity of the air around the transformer.


8、Transformer oil release and gas replacement should be recorded for the transformer exposure time. With oil custody of the transformer, from the beginning of the oil discharge.


Gas storage of the transformer, from the uncovering or open any blockage, to the start of vacuum or oil injection.


9、Transformer open air time should meet the following requirements.


When the relative humidity of the air is less than 75%, transformer exposure time shall not exceed 16 hours.


Regulating switching device air exposure time to comply with the provisions of Table 2.4.2 time.


Regulating switching device air exposure time



Ambient temperature (C)>0>0>0<0
relative humidity(%)Below 6565~7575~85 not control
Duration not greater than (h)2416108



10、dry air can be used to heat the air filtered by silica gel tank to make.


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