II. color changers and odor abnormalities
Many faults of transformers are often accompanied by heating, causing changes in color and temperature of the heating part or issuing special odors.
1. Overheating of the connecting part of the external wire clamp.
Caused by loose screws of the transformer bushing outlet clip itself or the fastening bolt with the connecting lead wire, oxidation of the contact surface or insufficient area, manifested as dark color and luster of the hot spot,
The temperature measurement will find that the temperature exceeds 70 degrees, the temperature wax is discolored, the surface paint is black, etc., the prevention of such defects can be combined with the power failure test to measure the DC resistance of the transformer winding including the wire clip, and the contact resistance of the wire clip itself can be measured separately when there is doubt (generally not more than 500u2).
When handling the contact surface according to the specific situation, grinding and tightening.
2. The silicone of the respirator is damp.
The silica gel of the respirator is generally color-changing, its role is to absorb the moisture into the conservator, under normal circumstances, the color is light blue, if it becomes pink, it is invalid. Generally, silica gel needs to be replaced once a year ;
Reasons and measures of silicone change color too fast:
1) silicone cylinder seal is not strict, such as rubber pad aging, screw loosening, glass cover cracks;
Replace the rubber gasket, and adjust the screws and glass cover.
2) The oil seal in the lower part of the silicone cylinder has no oil or low oil level, and the water in the oil seal makes the air enter the respirator directly without oil filtration.
Add the right amount of transformer oil.
3) The weather is rainy and the humidity is high or the water in the silicone cylinder can also speed up the color change of the silicone.
Similarly, if the silicone discoloration is too slow, it indicates that the breathing is abnormal, and the pipeline needs to be checked and processed.
3, transformer light gas action, gas relay oil room set gas.
Under normal circumstances, the transformer gas relay oil room is full of transformer oil, once the light gas action, should immediately check and take an oil sample chromatographic analysis to confirm whether the internal fault situation.
If the gas is colorless, odorless, and non-flammable, it is air;
Causes and measures:
1) After installation or maintenance, the new oil or filter oil will bring the gas into the transformer tank, and the gas is not repeatedly deflated or not completely deflated during the static period. Once the transformer is put into operation, the temperature rises, the gas expands and escapes, and enters the gas relay;
Therefore, the oiling procedure of the transformer should be strictly enforced and the gas should be deflated repeatedly.
2) The oil pump is poorly sealed, and the gas is brought into the transformer body, and the oil pump should be checked and excluded one by one.
If the gas contains odor, it indicates that there is an internal fault in the transformer, and the operation inspection and test should be stopped immediately. The general performance is: a. slight yellow and non-combustible, and the internal insulating support and other wood materials are burned; b. Black, gray, and combustible, bare metal overheating or insulation flashover to decompose the transformer oil; c. White and not easy to burn, maybe insulation breakdown or paper insulation burning.
The above phenomenon, gas sample, and oil sample chromatographic analysis, the characteristic gas will exceed the standard, should be combined with the electrical test and characteristic gas content, according to the test procedures and image spectrum guideline for comprehensive analysis, identify the cause, and then deal with.
