Running transformer core grounding defect cause analysis

Running transformer core grounding defect cause analysis - 2019 03 - 30 15:05:35 during normal operation, power transformer winding, there is electric field around the core and pieces of metal component in electric field, if the iron core is not reliable grounding, will produce discharge phenomenon, damage the insulation. Therefore, iron core must be reliable grounding, if core in another place, for some reason to form a closed loop, is normal to the leads of the ground will be circulation. One aspect shorting core local overheating and even partial loss; On the other hand, due to the normal ground wire core circulation, cause local overheating transformer, also may produce discharge fault. Therefore, accurate, timely diagnosis of transformer core earth fault and take positive measures to for system safety and stable operation is of great significance. Large power transformer in the process of running, happened iron-core earthing defects mainly include the following aspects. ( 1) Transformer in the process of manufacturing or repair, if iron wire brush, the reuse of broken strands wire rope and tiny metal wire is left in the transformer oil tank, when the operation of the transformer, the suspended solids under the action of electromagnetic field, the formation of conductive bridge, iron core and the sub tank, this kind of situation often occurs in the bottom of the tank. ( 2) Submersible pump bearing wear of the metal powder into the main transformer oil tank in iron core and sub tank. ( 3) Transformer oil tank, and radiator in the process of manufacturing, due to the welding slag cleaning not thoroughly, when the operation of the transformer, the oil flow under the action of the impurities are piled up together, make the core and the sub tank, this kind of situation easily in the strong oil circulating cooling transformer. ( 4) With metal debris on the iron core, the insulating oil within the core or core and sandwiched between a short answer. ( 5) At the bottom of the transformer into the water to make iron core insulation block be affected with damp be affected with damp, iron core over the ground insulation decline. ( 6) Core pieces of shoes and iron yoke under the insulation board between wear loss caused clip into the silicon steel sheet. ( 7) Clip itself is too long or loose core positioning device, the device after he had a shock displacement, clip into the tank wall. ( 8) Under a plate of small iron core column or the distance of the iron yoke, in suffering shock displacement after a collision. ( 9) Upper and lower iron yoke on the surface of silicon steel sheet for wave protrusions, and steel seat cover or a collision. ( 10) Wear heart tie belt screw or metal insulation damage, encounter with iron core or clip, etc.