According to statistics, the failure of on-load voltage regulating switch mainly includes two aspects: one is the failure of driving mechanism of voltage regulating switch, mainly including electric linkage, water inlet of box body, oil leakage of gear box, insufficient energy storage of spring, etc. Two is the switch body failure, mainly including oil leakage chamber, fastener loosening, contact movement stuck, contact wear resulting in poor contact, etc.. The common faults of on-load voltage regulating switches are listed and analyzed as follows.
1. Switch driving mechanism is faulty
① Motor failure. When the operating power supply is off or the motor circuit has problems, it will cause the failure of the switching electric mechanism, resulting in the lifting contact can not operate.
(2) The elasticity of spring energy storage mechanism becomes weak. Spring long-term deformation operation, coupled with the thermal effect of the current, so that the elasticity of the spring is weakened, causing the transmission mechanism is not in place.
2, switch body failure
Contact hair heat wear. On-load voltage regulating switch with load current to achieve voltage regulation. In the process of regulating the pressure, the gear change, so that the contact mechanical wear, electrical corrosion and other problems. As the contact resistance increases, the heating increases, which accelerates the corrosion and mechanical deformation of the contact surface, resulting in switch damage.
② Switch switch refuses to move or switch not in place. Due to insufficient power or obstruction, the switch is not switched in place and stays in the middle position for a long time, which can lead to continuous heating of transition resistance, resulting in transformer trip and power supply interruption.
③ Oil leakage in oil chamber. The oil chamber with load tap switch is a separate fuel tank. In operation, the oil in the oil chamber of the on-load tap switch is not allowed to enter the transformer body. When the switching switch runs, the arc is generated, so that the oil in the oil chamber deteriorates, and the oil can not enter the transformer body.
(4) deterioration of oil quality. The electric arc generated during the operation of the on-load voltage regulating switch causes oil deterioration and the insulation level of the switch decreases. Transformer oil has the functions of insulation, arc extinguishing, cooling, lubrication and corrosion prevention. The deterioration of oil quality will produce free carbon, hydrogen, acetylene and other gases and oil scale. Most of the gas is generally discharged from the insulating oil, but some of the free carbon particles and oil scale will be mixed in the insulating oil, and the other part will accumulate on the surface of the insulating parts of the switch, which will reduce the insulation level of the switch. The transformer voltage regulating switch is the only rotating parts of the transformer, it is easy to cause the failure of the machine because of poor contact fever, for this kind of switch failure is very easy to occur, we should be prepared to deal with this kind of fault can usually be checked and distinguished from the following aspects:
(1) There is no burn mark (burning) and bad contact phenomenon on the fixed and movable contact surface, and there is no grease scale at the contact point.
(2) whether the transmission mechanism of the pressure regulating switch is flexible; The transmission mechanism is too loose so that the pointer tip on the box cover indicates the position sign, and the contact is not closed at this time; Whether the switch three-phase contact is closed at the same time, whether the spring tightness is the same.
(3) whether the joint between the switch operating rod and the box cover is tight and whether the liner is complete; There is no water stain under the box cover hole of the aligning lever.
(4) If the tap joint of wiring plate is used, the tightness of the pile head of the wiring bolt should be checked, whether there is sludge accumulation between the pile heads of each wiring, to ensure that the pile head is clean and intact, otherwise it is easy to short-circuit or flashover traces.
(5) when checking the transformer load switch, the core part of the switch should be taken out, rotate back and forth, observe whether the action of the contact limit is smooth and coherent, and check the transition resistance to determine whether the connection is stable and reliable.
Wuhan Xinshengneng Technology Co., LTD
