Operating Regulations for High Voltage Circuit Breakers
1、 General requirements for high-voltage circuit breakers
1. The Circuit Breaker should operate within the specified technical parameters.
2. Circuit breakers must be equipped with reliable operating and closing power sources.
3. Power transmission should first close the knife switch and then close the circuit breaker; Before cutting off the power, disconnect the circuit breaker and check if it has been disconnected before pulling the knife switch.
4. The inspection of 110kV high-voltage equipment can be carried out by one person, but the distance from the charged body should not be less than 1.5 meters.
5. 6kV switch operation regulations:
1) The switch should be maintained every 2000 operations, major repairs should be carried out every 10 years or 6000 operations, and minor repairs should be carried out for 20 accidents and disconnections (or according to the switch manual);
2) After the switch maintenance, the handcart should be pushed to the test position for tripping and closing once each. Switches that refuse to trip during electrical operation are prohibited from being put into operation;
3) The on duty personnel are prohibited from grabbing the contact arm during operation;
4) When the cable room of the switchgear needs maintenance, the circuit breaker handcart must be disconnected before the handcart can be withdrawn. At this time, the voltage display light on the outgoing line installed on the switchgear does not light up. After confirming that there is no voltage, the grounding knife switch can be closed (at this time, the electrical inspection can be carried out at the static contact of the lower part of the handcart room).
6. Inspection items for Vacuum Circuit Breakers:
1) Check for any cracks, damage, discharge marks, or dirt on the insulated porcelain pillar.
2) Check the insulation rod, which should be intact and free of cracks. Each connecting rod should be free of bending. When the circuit breaker is in the closed state, the spring should be in the energy storage state.
3) Check for overheating at the contact of the connector and whether the lead relaxation is appropriate.
4) Check whether the opening and closing position indications are correct and consistent with the actual operating conditions at that time.
7. Special inspections are required for circuit breakers:
1) After the operation or tripping of the circuit breaker;
2) When the weather is abnormal;
3) When overloaded or overvoltage occurs;
4) When the circuit breaker operates abnormally;
5) Newly put into operation circuit breaker.
8. 6kV equipment inspection items:
1) Check that the simulated screen indicator light is consistent with the actual position;
2) Check that the opening and closing indicator signs and signal lights on the switchgear are consistent with their actual positions;
3) Check that the live display of the power transmission interval is correct;
4) Check that there are no abnormal sounds inside the 6kV switch room;
5) The grounding transformer and arc suppression coil have no abnormal sound, and the joints have no heating phenomenon;
2、 Preparation work before power transmission
1. Retrieve the work order, complete the process, give instructions, remove temporary measures, and restore fixed safety measures.
2. In the following situations, disconnect the knife switches on both sides and measure the insulation:
1) Newly invested equipment;
2) Devices that have been out of service for more than a month;
3) When there is obvious dampness or suspicion of low insulation.
3. After maintenance, the switch was tested successfully in the whole set with the knife switch disconnected (or the handcart in the test position).
4. Before powering on the circuit breaker, the following checks should be carried out:
1) Sf6 Circuit Breakers should be checked for normal gas pressure.
2) Porcelain bottles, sleeves, and bodies should be clean, without damage or leakage;
3) The opening and closing position indicators should be correct;
4) The phase partition should be intact and undamaged;
5) The grounding wire of the shell is in good condition;
6) The operating mechanism should be clean, the mechanical lever pin should not fall off, the pull rod porcelain bottle should be flexible and not broken, and the arc extinguishing cover should be upright;
7) There are no tools left on the switch body, and the work site should be clean;
8) The fixed fence should be intact, and the door should be tightly closed and locked;
9) The tripping iron core and closing contactor should be flexible without any jamming phenomenon;
10) The closing insurance should be intact, and the rated current of the insurance should comply with relevant regulations.
3、 Operation of Circuit Breaker
1. Basic requirements for operating circuit breakers
1) The circuit breaker has no defects that affect safe operation. The breaking capacity of the circuit breaker should meet the requirements of the short-circuit current of the busbar. If the breaking capacity of the circuit breaker is equal to or less than the short-circuit current of the busbar, there should be a metal partition or wall isolation between the circuit breaker and the operating mechanism. Remote operation should be carried out when conditions permit.
2) The circuit breaker position indicator should correspond to the indicator light signal and meter indication.
3) Before closing the circuit breaker, the relay protection should be checked and activated according to regulations. Before disconnecting, the arrangement of the load carried should be considered.
4) It is generally not allowed to manually and mechanically close circuit breakers.
5) When the gas pressure of SF6 circuit breaker reaches the blocking pressure, it is prohibited to operate the circuit breaker.
6) When the number of circuit breaker trips approaches the maintenance cycle, the automatic closing device needs to be released.
7) When operating, the control switch should not return too quickly. It should be released after the red and green light signals are issued to avoid the opening and closing coils being energized for a short time and refusing to move. The electromagnetic mechanism should not return too slowly to prevent auxiliary switch failure and burning of the closing coil.
8) After the circuit breaker is closed, it should be confirmed that all three phases have been connected and the automatic device has been set according to regulations.
2. Key inspection items when operating circuit breakers
1) Check the position of the circuit breaker based on current, signal, and on-site mechanical indications;
2) Circuit breakers with meters (real-time monitoring) should be checked item by item for current, load, and voltage conditions;
3) Before operation, check whether the hydraulic circuit of the control circuit and auxiliary circuit control power supply is normal, and check whether the power mechanism is normal. If the energy storage mechanism has already stored energy, the switch is ready for operation;
4) Long term shutdown circuit breakers should undergo 2-3 trial operations through remote control before formal operation; Only after there are no abnormalities can the proposed operation ticket be accepted for operation;
5) When abnormal situations are discovered, operators and professionals should be immediately notified and relevant handling should be carried out.
3. General sequence of power transmission operation
1) Check if the switch is open;
2) Input AC/DC insurance (or secondary switch);
3) Push the handcart into the running position (or follow the principle of first closing the power side and then closing the load side, and close the corresponding knife switch of the switch);
4) Then the corresponding closing operation can be performed.
4. General sequence of power outage operations
1) Disconnect the switch, the green light is on, and check the meter reading;
2) Check if the switch is open;
3) Pull the handcart out of the cabinet (or follow the principle of disconnecting the load side first and then the power side, and open the knife switch of the switch);
4) Disconnect the power supply for operation.
5. High Voltage Circuit Breakers allow manual (mechanical) tripping in the following situations:
1) The switch refuses electric tripping;
2) Serious personal or equipment accidents require emergency disconnection;
3) Perform debugging work after power outage.
6. High voltage circuit breakers are prohibited from manually closing (mechanical closing) under load. When manual closing is necessary for accident handling, approval must be obtained from the leader or dispatcher of the operation department.
7. When the circuit breaker is not fully opened due to mechanical reasons (in a semi open state), it should be manually closed immediately and reported to the operation department.
4、 Inspection and maintenance of circuit breakers
1. During the inspection of a circuit breaker in operation, in addition to checking the items before power transmission, the following items should also be checked:
- 1) The circuit breaker itself and its mechanical parts have no signs of fracture, deformation, or other phenomena;
- 2) The casing has no rupture or discharge phenomenon;
- 3) Whether there is overheating and discharge phenomenon;
- 4) The secondary circuit is not loose, and the auxiliary contact position should be correct;
- 5) Check that the circuit breaker has no noise.
- 6) Close the switch cabinet door properly.
2. After a circuit breaker accident trips, the following checks should be performed:
- 1) There are no signs of heating, burns, or deformation at each joint;
- 2) The main contact of the air switch should be checked for any burn damage, and the mechanical parts of the machine should be intact and in good condition.
- 3) The switch in standby mode has its knife switch in the closed position.
- 4) The inspection items for switches in standby should be the same as those for operating equipment.