Two of the major causes of transformer core magnetic circuit fever
Two of the major causes of transformer core magnetic circuit heat - 2019 03 - 30 15:05:33 transformer core heat failure can make the decomposition of transformer oil, so the transformer iron core transformer oil chromatographic analysis can determine whether fever down. Transformer core magnetic circuit heating is one of the transformer core heat failure. Caused by the transformer core magnetic circuit of the main causes of fever, there are two. 1, the iron core multipoint earthing transformer core magnetic circuit caused by fever if transformer core is not grounded, between high and low voltage winding, low voltage winding and transformer core, iron core and the earth ( Transformer oil tank) There is between the parasitic capacitance. When the transformer core and transformer substation grounding system reliable connection, the parasitic capacitance between the core and the earth was short circuit current, make the iron core is zero, then flows in the ground electric winding capacitance of core flow, for three-phase transformer, because of the three-phase symmetrical three-phase voltage is symmetrical, so the sum of three-phase winding capacitance current of iron core is almost equal to zero. So, need a grounding transformer core. When the transformer core or with other metal components, there are two or more than two grounded the pick up location will form a closed loop, cause the circulation, the current will cause local overheating, lead to oil decomposition, may also make the ground lug fusing, or burn out transformer core, transformer cannot continue running. 2, transformer core magnetic flux leakage in the transformer core magnetic circuit heating transformer core winding magnetic flux, including the main magnetic flux and leakage magnetic flux, both the main magnetic flux and magnetic flux leakage, can be divided into axial component and radial component. Axial component distribution is simple, highly variable pressure along the winding is small, complex radial component along the winding height distribution, uneven distribution of eddy current loss caused by it, and the changes over the transformer capacity, not only change with axial height of the winding, also with the winding radial size changes, its value appears near the end. As a result of the transformer winding near the iron core, magnetic flux leakage of radial values higher than the outer winding. If transformer winding is low, medium, high, low voltage winding high radial magnetic flux leakage. In large transformer, the magnetic flux leakage density is high, so the stray loss is very big, sometimes up to hundreds of kilowatts, cause local overheating. This is two main cause of transformer core magnetic circuit fever.