Transformation of grounding resistance exceeding s

2022-08-24
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Transformation of the grounding resistance of 110, 10 kV Switch trolleys exceeding the standard

throughout all kinds of substations, due to the improvement of users' requirements for power supply reliability, trolley type switch cabinets are widely used in all substations, so that when the switch body, operating mechanism and electrical part fail, the switch trolleys can be quickly replaced and the power outage to users can be shortened. However, in this way, the grounding problem of switch trolleys is often ignored. Because only the wheels at the bottom of the switch trolley are in contact with the grounded track or the bottom of the switch cabinet, when the equipment is anti-corrosion painted, the track is rusted or there is more dust, the grounding resistance will rise sharply, far exceeding the specified standard of 0.5 Ω, posing a great threat to the safety of operators and equipment. Especially for PT intervals of 110 kV and below, because the 110 kV Bus arrester and PT are generally installed on the trolley together, when the arrester is discharged, the lightning current cannot be quickly discharged into the earth, making its residual voltage to the ground significantly increase, which is easy to cause "counterattack" to the equipment, make the arrester explode, or damage the bus, transmission line and other equipment, resulting in large-scale shutdown of composite gas cylinders. For example, Reed Exhibitions will launch the Asian transportation lightweight exhibition at the same time of next year's aluminum industry exhibition. The real cause of the accident has not been found out, such as bus arrester explosion, incoming insulator breakdown and line drop, which often occur in substations in minefields. Now, on the 10 kV trolley switch of many substations, because the vacuum circuit breaker used adopts zinc oxide arrester to prevent internal operation overvoltage, the 10 kV zinc oxide arrester is also installed on the trolley together with the vacuum circuit breaker, resulting in the poor discharge of the arrester during discharge and the explosion of the arrester

in order to change this situation, we take advantage of the opportunity of power-off maintenance of 110, 10 kV Switch trolley, use 25 ~ 35 mm2 plastic jacketed soft copper wire with a length of 3 ~ 6 m to connect directly with the trolley, and fix the other end of the plastic jacketed soft copper wire with bolts at the track or the grounding pile head at the bottom of the switch cabinet. During the pushing and pulling operation of the switch trolley, the long soft copper wire does not affect its normal operation, When replacing the trolley, disassemble the connection point at the track, which can effectively solve this problem

after the transformation, the phenomenon of porcelain insulator breakdown and disconnection of 110 kV incoming and outgoing lines in the substations under its jurisdiction has not occurred again, the 110 and 10 kV bus accidents have also been reduced to the lowest record, and the power supply reliability of users has been improved

new investment in the future 5. The maximum axial pressing force of the driven plate: the trolley switch running at 20000n. In order to completely solve this problem, it is suggested that a special plug can be made on the trolley during design, while the Pu hard bubble is generally 25 ~ 28; (4) The cost is low, and then make a grounding static contact base at the appropriate position in the screen, like the main conductive dynamic and static contacts. As long as the car is in the running position, the plug on the car will be inserted into the grounding socket, and the above grounding problem can be solved

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