1. equipment anomalies

 

35 kV flyover transformer main transformer for the SZ9-3150 / 35, September 1999 factory, equipped with on-load regulator for the SYJZZ-35 type, the transformer in January 2000 put into operation.

 

July 29, 2005, in the cycle of the transformer pre-test, found that the transformer insulation resistance, leakage current and other data failed.

 

2. The main factors affecting the main insulation anomalies

 

The main transformer of the previous test on the date of April 29, 2002, the main insulation test report and March 2004 oil sample supervision test results are normal. According to the above results of the test data analysis, high pressure side of the insulation to the ground, the main factors affecting the transformer main insulation anomalies are summarized below.

 

The transformer body oil pillow part of the seal bad water, resulting in the body insulation oil water content; with switch switch oil pillow part of the bad seal water, resulting in the internal switch oil insulation oil inside; Internal insulation oil carbonation serious; due to the transformer body insulation oil content of large, high-pressure coil surface moisture caused by poor insulation; on-load tap-changer switch insulation oil content, resulting in the switch insulation bucket (due to the part of the high side Ground insulation is a unique part); high-voltage coil to the on-load tap-changer tap wire insulation damp, ground distance is not enough and so on.

 

3. On-site inspection and oil test found problems

 

Maintenance and oil testing technical staff, on-site inspection of the transformer and the transformer oil sampling test, found the problem.

 

There is no transformer oil in the lower part of the respirator oil, loss of oil seal effect; transformer body insulation oil sampling test, pressure test values ​​meet the operating standards; Switch body insulation oil sampling test, the average voltage value of only 1.8 kV; on the body and the load switch seal parts of the inspection intact, no signs of oil and water.

 

Through the field inspection and oil pressure test results, to determine the first on-load switch hanging core inspection, hanging core found the following problems.

 

(About 10 g) and rust in the gas relay. Open the on-load tap-changer cover and find that the upper part of the on-load switch has the deposited water. Will be loaded switch box inside the transformer oil after the end of the tank at the bottom of the water, about 100g; open the switchboard storage tank side door, the storage tank has about 20 g of water and serious corrosion.

 

Site on the carry switch parts of the careful inspection, clean up, and qualified with a number of transformer oil rinse, the correct installation of breathing apparatus, the test results are normal.

 

4. Cause the transformer main insulation error reasons

 

By field inspection analysis, resulting in the transformer main insulation abnormalities caused by the respirator.

 

Inverter switch oil conservator respirator lower oil cup without transformer oil, respirator silicone long-term direct contact with the air, has been seriously discolored loss of moisture absorption, with switch oil pump inside the transformer oil directly in the air, respirator Loss of function, is caused by the transformer main insulation abnormalities of the main factors.

 

Flyover transformer is located in the deep mountain depression, the temperature difference, humidity, due to the loss of the transformer oil transformer and air isolation, long-term internal and direct contact with the atmosphere, wet air long-term direct access to the oil conservator, with temperature The formation of condensation, condensate into the water inside the on-load switch body, the transformer oil water content increased, oil quality deterioration, dielectric strength decreased, is the main cause of transformer insulation failure of the direct cause. 

 

5. Operation and maintenance should pay attention to the problem

 

Through the equipment test data anomalies and analysis and processing, the transformer operation and maintenance should pay attention to the following points.

 

The operation of the duty officer should strengthen the sense of responsibility, carefully check the situation of equipment and found abnormal phenomena in time to eliminate and eliminate hidden dangers; installed with a respirator of outdoor equipment, to strengthen the maintenance check, pay attention to observe the respirator silicone color, found that color changes should be carried out Replacement; replacement of silica gel, it must be noted that the bottom of the respirator must be marked by the volume or volume, containing more than one-half of the transformer oil to prevent the silicone inside the respirator and the atmosphere directly connected to the impact of life, silica gel , The air directly into the conservator, resulting in deterioration of the transformer oil or the formation of condensation, hazardous equipment, safe operation. Especially humidity and rainy season, should always check the color of the respirator silicone, find changes, replace immediately, and install it correctly.