Overview: Isolation switch is a device without interrupter switchgear is mainly used to break the circuit no load current, isolated power supply state in the sub-gate marked off points to ensure the safety of other electrical equipment maintenance . In the closing state can be reliably through the normal load current and short circuit fault current. Because it has no special interrupter device, can not cut off the load current and short circuit current. Therefore, the isolation switch can only be disconnected at the circuit breaker has been the case to operate, non-load operation, so as not to cause serious equipment and personal accident. Only voltage transformer, lightning arrester, exciting current of not more than 2A of the load transformer, current does not exceed the load line 5A to direct operations with the isolation switch.

High voltage isolation switch can be separated into indoor and outdoor type and style of two.

Outdoor high-voltage isolation switch operation, often by wind and rain, snow and ice, the impact of dust, poor working environment. Therefore, outdoor-type isolation switch higher, should have anti-ice capability and high mechanical strength. At different voltage levels of the system, are required to use the isolating switch, the isolation switch is also a corresponding voltage level. 35kV and higher voltage switches used in isolation, generally are three-phase linkage type, can be divided into the manual mode of operation, electric operation, compressed air operation and hydraulic operation. Isolating switch can also be used for earthing switches used.

10kV outdoor-type isolation switch into manual linkage type and single-phase three-phase direct action type.

Indoor-type isolation switch, generally three-phase linkage type, manual operation, the complete power distribution device, installed on the circuit breaker bus-side and load side or used as a grounding switch.

(2) isolating switch applications: When the isolating switch and circuit breakers, earthing switches used in conjunction with, or isolation switch with ground function itself should be mechanical or electrical interlocking chain to ensure the correct procedures;

closing, the confirmation circuit breaker in the sub-gate devices such as switch position, to close the isolation switch, closing the end of action, not too hard to avoid the impact;

If unipolar isolation switch, closing should be the first joint on both sides with the latter co-intermediate phase; sub-gate should first pull the middle phase, then pull both sides of the phase of operation must use insulated rod to operate;

Tripping, the confirmation circuit breakers switching equipment in the sub-gate position, should slow operation, when switching from fixed contact when the surgeon opened quickly. After the operation, should ensure that isolation switch is in the off position, and firmly maintain the lock operating mechanism;

with isolation switch to cut off the transformer load current, overhead line and cable charging current, loop current and a small load current, shall be promptly sub-gate operation, in order to achieve rapid and efficient interrupter;

transmission should be the first joint supply side of the isolation switch, after the combined load side of the isolating switch; power when in reverse order;

isolation switch allows direct operation of the project:

1) open circuit in voltage transformers and surge arresters;

2) voltage of 35kV, a length of no-load operation within 10km of overhead lines;

3) voltage of 10kV, a length of no-load operation within 5km of cable lines;

4) voltage of 10kV the following, non-load operation of the transformer, the capacity of not more than 320kVA;

5) voltage of 35kV the following, non-load operation of the transformer, the capacity of not more than 1000kVA;

6) opening and closing bus and directly connected to the bus on the device’s capacitive current;

7) open, co-transformer neutral grounding line, which of points connected with coil, only a short circuit fault in the system not only allows the operator;

8) in parallel with the bypass circuit breaker isolating switches, circuit breakers in the closing position, in order to operate;

9) open, co-excitation current does not exceed 2A load transformer and capacitor current no-load no more than 5A lines on voltage of 20kV and above must use three-phase linkage isolation switch;

10) three-phase linkage with outdoor disconnecting switch, opening and closing voltage of 10kV or below, the current is below 15A load current; and 70A of the loop does not exceed the current balanced;

11) Do not use indoor pull isolation switch three-phase interaction, co-system loop current.

misuse isolation switch, causing the negatively Hera, co-isolation switch, according to the following provisions:

1) When the wrong pull isolation switch, arc found in the incision should be closed quickly; if opened, does not allow re-closed, if the pole isolation switch, the operation and found the wrong one phase pull, while the other two phase should not continue to operate, and report the relevant departments in a timely manner;

2) When the wrong co-isolation switch, whether caused by accident, do not allow re-opened, because with a load pull isolation switch, three-phase arc will cause a short circuit, and promptly report to relevant departments to take necessary measures .

(3) isolation switch operation and maintenance:

isolation switch operation: Isolation switch should be installed simultaneously with the normal distribution visit:

1) Check the temperature of isolation switch contact parts are overheating;

2) Check whether insulator damage, cracks and signs of discharge, with or without insulator in the bonding office signs off;

3) check the 10kV overhead lines with a single-phase isolation switch blade locking device is intact.

isolation switch maintenance items: 1) clean ceramic surface of the dust, check it off the surface of glazed ceramic pieces, broken, with or without signs of cracks and flashover, insulator iron, porcelain is strong binding sites. If serious damage should be replaced;

2) Clean the blade with gasoline, contact or touch refers to the oil, check the contact surfaces are clean, with or without mechanical damage, and signs of oxidation and thermal distortion, deformation phenomena;

3) Check the blade contact or attachment are complete, no damage;

4) Check the connection and bus isolation switches, circuit breakers of the lead is solid, with or without overheating;

5) Check whether the software to connect parts folded, broken unit and so on;

6) Check and clean operating mechanism and the transmission part, and add an appropriate amount of lubricating grease;

7) Check the live transmission part and whether the distance requirements; positioning device and brake device is a solid, action is correct;

8) Check whether the good base isolation switch, grounding reliability.

isolation switch to prevent misuse: 1) in isolation switches and circuit breakers should be installed between the mechanical interlocking, usually in linkage to ensure that the circuit breaker in the closing position, so that isolating switch can not be sub-gate;

2) use of the oil circuit

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