1. Overview:

Disconnector is a kind of switching equipment without arc extinguishing device, which is mainly used to disconnect the circuit with no-load current and isolate the power supply. When the switch is off, there is an obvious disconnection point to ensure the safety inspection of other electrical equipment. In the closing state, normal load current and short-circuit fault current can be reliably passed. Because it has no special arc extinguishing device, it can't cut off the load current and short-circuit current. Therefore, the disconnector can only be operated when the circuit has been disconnected by the circuit breaker, and it is forbidden to operate with load to avoid serious equipment and personal accidents. Only voltage transformers, lightning arresters, no-load transformers with excitation current less than 2A, and no-load lines with current less than 5A can be directly operated by disconnectors.

High-voltage disconnectors can generally be divided into outdoor and indoor types.

In the operation of outdoor high-voltage disconnector, it is often affected by wind and rain, snow and dust, and the working environment is poor. Therefore, the requirements for outdoor disconnectors are higher, and they should have anti-icing ability and high mechanical strength. In systems with different voltage levels, disconnectors are needed, so disconnectors also have corresponding voltage levels. Generally, the disconnectors used in the voltage level of 35kV and above are of three-phase linkage type, and the operation modes can be divided into manual operation, electric operation, compressed air operation and hydraulic operation. The disconnector can also be used as a grounding switch.

10kV outdoor disconnectors are divided into manual three-phase linkage type and single-phase direct control type.

Indoor disconnectors, usually of three-phase linkage type, are manually operated. They are installed on the bus side and load side of circuit breakers or used as grounding switches in complete power distribution equipment.

2. Application:

(1) when the disconnector is used in conjunction with the circuit breaker and grounding switch, or when the disconnector itself has grounding function, there should be mechanical interlock or electrical interlock to ensure the correct operation procedure;

(2) when closing, the disconnector can only be closed after confirming that the switching devices such as circuit breakers are in the opening position. At the end of the closing action, the force should not be too large to avoid impact;

If the single-pole isolating switch is used, the two sides of the phase should be closed first, and then the middle phase should be closed; When opening the brake, the middle phase should be pulled first, and then the two sides should be pulled. When manipulating, the edge bar must be used to manipulate;

(3) break-brake, confirm the circuit breaker and other switching devices in the break-brake position, should be slowly manipulated, and quickly open when the main switch leaves the static contact. After the operation, ensure that the isolating switch is in the off position and keep the operating mechanism locked;

(4) When disconnecting switch is used to cut off the no-load current of transformer and crowd out the charging current, loop current and small load current of lines and cables, switch-off operation should be carried out quickly to achieve quick and effective arc extinguishing;

⑤ When sending power, the isolating switch on the power supply side should be closed first, and then the isolating switch on the load side should be closed; When power is cut off, the order is reversed;

6. Disconnector promised to direct manipulation of the project:

1) Open and close the circuit of voltage transformer and lightning arrester;

2) No-load operation crowded line with voltage of 35kV and length of less than 10km;

3) No-load cable lines with a voltage of 10kV and a length of less than 5km;

4) The capacity of transformer with voltage below 10kV and no-load operation shall not exceed 320kVA；;

5) The capacity of transformer with voltage below 35kV and no-load operation shall not exceed 1000kVA；;

6) Capacitive current of the bus and the equipment directly connected to the bus;

7) Open and close the grounding wire of the neutral point of the transformer. When the neutral point is connected with the arc suppression coil, it can only be operated when there is no short circuit fault in the system;

8) The bypass disconnector connected in parallel with the circuit breaker can only be operated when the circuit breaker is in the closing position;

9) Open and close the no-load transformer with excitation current not exceeding 2A and the no-load line with capacitance current not exceeding 5A. When the voltage is 20kV or above, three-phase linkage disconnector must be used;

10) Use outdoor three-phase linkage isolating switch, with the opening and closing voltage of 10kV and below, the current of load current below 15A and the loop equilibrium current of no more than 70A;

11) It is forbidden to use indoor three-phase linkage isolating switch to pull and close the loop current of the system.

⑦ Mismanipulation of the disconnector, causing the disconnector to be pulled or closed with load, shall be handled according to the following provisions:

1) When the disconnector is pulled wrongly, it should be closed rapidly when the arc is found in the incision; If it has been opened, it is not allowed to be closed again. If it is a unipolar disconnector, it is found that it is pulled incorrectly after manipulating one phase, while the other two phases should not continue to be manipulated, and the situation will be reported to the relevant departments in time;

2) When the disconnector is misplaced, no matter whether it causes an accident or not, it is not allowed to open it again, because opening the disconnector with load will cause three-phase arc short circuit, and report it to the relevant departments quickly so as to take necessary measures.