Custom Soft Magnetic Materials and Transformer Manufacturers in China


4 big cause of transformer core heating failure ( On)

by:Transmart     2021-01-18
4 big cause of transformer core heating failure ( On) 2019 - 03 - 30 15:06:02 transformer core and winding is a major part of the electromagnetic energy transmission, exchange, iron core transformer is in good condition and reliable operation of the key. Grounding transformer core is to prevent the transformer in operation or experiment, due to the electrostatic induction on the iron core and other metal artifacts have suspended potential cause of discharge, so the iron core and its metal components in addition to wear heart screw, must be reliable grounding and iron core lamination run only a little, if there are two above ground, the ground loop can be formed between. When the main track through the closed loop, in which will produce loop current, internal overheating caused by accidents. Core heating failure mode can be divided into: iron core multipoint earthing, core grounding short circuit between bad, iron chips and winding short-circuit core fever caused by the fault. According to core heat degree can be divided into low overheating, medium temperature overheating, high temperature overheating. Overheating fault is sometimes slow growth, when growth to a certain degree will be stable in a certain numerical; Sometimes suddenly appeared and the initial value is higher, and faster growth. Internal overheating fault occur, a short while not immediately affect the safe operation of the transformer, but development bottom go to, the initial state is higher, especially for overheating growth and faster fault, if not controlled and solved, it may be big problems, serious will threaten the safe operation of the transformer. Therefore, to strengthen the monitoring and control in operation of the transformer and overheating fault in time and accurate judgment, processing, to safe and economic operation of the transformer has the extremely vital significance. A, the iron core short-circuit caused by local overheat (1) the internal parts fall off when the pilot test in the transformer oil chromatography, found that the higher total hydrocarbon content increase, oil chromatogram is suddenly, through the three ratio to total hydrocarbon content of component analysis, the conclusion is: transformer internal defects bare metal high temperature overheating. Maintenance staff use pliers type current meter, respectively to the operation of the transformer core and clamp earth current in the electric measurements, found no grounding current, which excludes the iron core, or between parts of a multipoint earthing fault. Then check the scene outside the body of the transformer and electrical experiment. Outside the body check is the main object check gas relay in ontology set chamber for gas evolution; Electrical experiment check main object is two parts, magnetic circuit and electric circuit experiment content is mainly remote sensing core and clamp, insulation resistance measuring winding dc resistance. Check and the experimental results showed the gas relay gas precipitation has been observed. Part of magnetic circuit wag found good insulation, insulation resistance iron core and multipoint earthing fault is not exist. Circuit of dc resistance experiment results demonstrated that high and low voltage direct current (dc) resistance were in normal range. According to the appearance of the site inspection and electrical experiment, the analysis of the possibility of overheating fault has two kinds: one kind is a core itself in short circuit; One is Japan's low voltage wire short circuit of itself. In order to find and determine the cause of the problem, the transformer pulled out a small amount of oil, the upper part of the core yoke iron exposed, then open the tank of the upper cover plate, the inspectors use of endoscopy, detecting the transformer body parts of internal check, check for abnormal found. Then on the yoke iron clamp for inspection, maintenance staff found in the upper phase coil, A low pressure above the pinout, do not pull on the iron yoke clamp board A fixed bolt equalizing cap is lost. So it is concluded that the cause of the problem: the pressure loss of iron cap caused more short circuit fault between iron chips, makes the iron core is formed between the short contact circulation, cause fever which can lead to excess levels oil chromatographic total hydrocarbon values.
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