The isolating switch is one of the key equipments indispensable for the power system. It is used to isolate the power supply and has a significant disconnection point, accounting for the largest proportion of substation electrical equipment. The general isolating switch has a simple structure and is installed on the power supply side and the load side of the short circuit breaker. Because it is mechanical, it often fails.
First, the phenomenon of failure is:
1, the contact part of the fault:
(1) Looseness due to loss of pressure due to the contact tightening member, resulting in poor contact heat generation and burning. The contacts of the knife gate are exposed to the air and are prone to oxidation and dirt.
(2) The knife gate will have an arc during operation, so it will burn, the contact surface of the static contact, the contact between the fingers and the finger joint is poor, resulting in poor contact of the contact surface and burnout.
(3) In the course of operation, the position is changed due to improper force, and the contact pressure is insufficient, resulting in poor contact and overheating of the contact. It can be determined according to the change of the color of the temperature indicator, or it can be determined according to the color of the contact, the spark generated, and the like.
2, porcelain bottles and mechanical parts:
(1) External insulation flashover.
(2) The porcelain column is broken.
(3) Three phases of different phases.
(4) The rotating part is rusted and cannot be pulled.
Second, the fault handling:
1, the treatment of contact overheating:
(1) Observe whether the temperature indicator is discolored or measured by an infrared thermometer. If the actual temperature of the contact exceeds the specified value (70 °C), it should be found whether it is caused by overload or contact failure. The isolation switch must be replaced if it is overloaded.
(2) Check the conductive part on the outside. If it is due to poor contact, it can be used to push the foot with the corresponding voltage level of the insulation rod to improve the contact situation and handle the condition when the power is off.
2, porcelain damage or serious flashover processing:
(1) Dispatchers should be reported immediately, power outages should be handled as soon as possible, and monitoring should be strengthened before power outages.
(2) If the porcelain piece has large damage or discharge, the upper level switch should be used to disconnect the power supply.
(3) It is forbidden to disconnect the load with the broken knife gate.
3. Rejection and closing treatment
(1) Refuse to pull the brake: When the knife gate cannot be opened, do not pull it hard. It should not be forcibly opened before the cause is found, otherwise it may cause equipment damage or break the porcelain bottle column. Apply for power outages in a timely manner.
(2) Rejecting the switch: When the knife lock cannot be closed, first check whether the lock and the operation sequence are in compliance with the regulations, and then check whether the shaft pin is off, whether there is any mechanical failure such as rotation. The motor-drive mechanism should check for electrical circuit failures such as loss of power of the motor.
Third, the maintenance of the isolation switch and view content:
1. The dirt on the surface of the insulator is removed, and at the same time, the damage or crack is checked. The iron cap and the porcelain piece are firmly bonded, and the connecting rod is in a proper position.
2. The contact surface of the contact is flat, no oxidation, no burn, and the spring of the static contact has no rust. If there is a slight burn, use a trowel to repair and clean with gasoline (no gauze is used, because the gauze particles will be embedded in the conductor to affect the electrical conductivity), then apply a layer of Vaseline or conductive paste; if the burnt is serious, the parts that cannot be trimmed It should be replaced in time.
3. The contact between the two contacts should be tight, and the pressure of the springs on both sides should be uniform.
4. After the isolation switch and the operating mechanism have passed the inspection and adjustment, the test operation should be carried out several times. When the mechanical handle reaches the end point, the disconnector must reach the closing end; when the handle reaches the end point, the disconnector must reach the end of the trip. After disconnection, the distance between the contacts of each phase and the blade is the same.
5. The terminal is in good contact and is firmly connected to the busbar. The isolation switch should not be subjected to mechanical stress.
6. All the parts that need to be fastened should be tightened. The action of the auxiliary switch in the operating mechanism should be correct and the position of the contact should be reasonable.
Rotate the limit pin to move freely, otherwise it can be treated with a loosening agent and then Vaseline lubricated.
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