Precautions for Transformer Oil Filtration
The construction area of the transformer should be fenced and warning signs should be hung.
Smoking and fireworks are strictly prohibited in the construction area of the transformer, and a carbonated sodium dry powder fire extinguisher should be equipped on site.
Before filtering the oil, it is necessary to check whether all equipment and components are reliably grounded.
Before construction, detailed technical and safety instructions should be given. Construction personnel should be familiar with equipment operation and construction procedures.
When the oil pipe is connected, it should be tightly tied without oil leakage or oil running.
During the transformer oil filtration process, the duty personnel should inspect the equipment status and oil system status, and keep records.
When receiving oil, calculate the total amount of oil received, allocate flushing oil and installation oil, and try to avoid wasting oil, ensuring that the transformer is filled with oil in one go.
Oil inspection is an important link. Since there is currently no better on-site inspection method, it can only rely on on-site personnel to judge visually and by smell. This work should be carried out by experienced construction personnel.
During the transformer oil filtration process, the manhole door of the oil storage tank should be sealed with plastic sheeting. The moisture absorber installed should be checked to ensure it is filled with oil according to the scale line at the bottom.
The outlet oil temperature of the oil filter should be no lower than 50℃ and no higher than 70℃.
Pay attention to the oil quality of the vacuum pump of the oil filter and replace it in a timely manner.
Pay attention to the oil level of the oil accumulation window of the oil filter and stop the machine in time to drain the oil.
Pay attention to the pressure gauge at the outlet of the oil filter screen, and replace the filter screen in time.
When the oil pipe is not in use, it should be immediately sealed tightly with plastic sheeting to prevent moisture and impurities from entering the pipe.
After filtering the oil into the oil storage tank, seal all outlets of the oil tank tightly with plastic sheeting in a timely manner.
Before the oil filter heater is put into operation, it is necessary to confirm that the oil level of the oil filter is normal. Before stopping the oil filter, turn off the heater first to prevent the heater from burning out and damaging the equipment.
Transformer Oil Standards
Before gas replacement, the purified oil for transformer should meet the following requirements after injection:
Transformer Oil National Standard GB2536-81 (new oil)
Transformer oil indicators in equipment (GB7595-87)
Note: The gas content in the oil is negotiated between the user and the manufacturer.
The insulation oil test should meet the following requirements:
The insulation oil test items and standards should comply with the provisions of Table 19.0.1.
The insulation oil test classification for new oil acceptance and filling electrical equipment should comply with the provisions of Table 19.0.2.
When mixing insulating oil is required, the mixed oil sample should be extracted and analyzed according to the actual usage ratio before mixing, and the results should comply with the provisions of items 3, 4, and 10 in Table 19.0.1. After mixing, the insulation oil should be tested according to the provisions of Table 19.0.2.
The gas chromatography analysis of the dissolved gas in the insulation oil should comply with the following requirements: for transformers with a voltage level of 63 kV and above, the dissolved gas in the transformer body insulation oil should be analyzed for 24 hours before boosting or switching on, and at rated voltage. The hydrogen, acetylene, and total hydrocarbon contents measured twice should not have a significant difference. The test should be carried out in accordance with the national standard "Transformer Oil Dissolved Gas Analysis and Judgment Guide."
The measurement of trace water in the insulation oil should comply with the following regulations: for transformers with a voltage level of 110kV, the trace water content in the transformer oil should not be greater than 20ppm; for transformers with a voltage level of 220~330kV, the trace water content should not be greater than 15ppm; for transformers with a voltage level of 500kV, the trace water content should not be greater than 10ppm.
The measurement of gas content in the insulation oil should comply with the following regulations: for transformers with a voltage level of 500kV, the gas content in the oil should be measured before the insulation test or the first voltage boost, and the value should not be greater than 1%.
Insulation oil test items and standards
Note: Item 11 is the standard for new oil, and the tgδ (%) standard after filling the electrical equipment is not greater than 0.7% when the temperature is 90℃.
Transformer insulation oil test classification
