High-voltage disconnectors are important equipment in power systems, mainly used to isolate circuits, ensure maintenance safety, and change operating modes. The following are its specific functions and operating points:
The role of high voltage isolating switch
Isolate power supply: When electrical equipment is under maintenance, isolate the electrical equipment under maintenance from the live power supply to form a disconnection point to ensure the safety of personnel and equipment.
Switching lines or busbars: Use isolating switches to switch electrical equipment or lines from one set of busbars to another set of busbars.
Closing and breaking low-current circuits: Closing and breaking voltage transformers, lightning arrester circuits; capacitor currents; unloaded power lines; unloaded transformers, etc.
12kV isolating switches allow closing and breaking of unloaded overhead lines below 5km: 40.5kV isolating switches allow closing and breaking of unloaded overhead lines below 10km and unloaded transformers below 1000kVA; 126kV isolating switches allow closing and breaking of unloaded transformers below 320kVA
Basic structure of disconnector
Conductive part: conducts current in the circuit, closes and opens the circuit. Contact, switch, terminal block
Insulating part: realizes insulation between live part and grounded part.Support insulator, operating insulator
Transmission mechanism: receives torque from operating mechanism and transmits motion to contact to complete opening and closing of disconnector.Crank, connecting rod, shaft gear or operating insulator
Operating mechanism: provides energy to the disconnector through manual, electric, pneumatic and hydraulic operation.
Support base: fixes conductive part, insulator, transmission mechanism, operating mechanism, etc. into one, and fixes them on the foundation.
Operation steps and precautions
1. Inspection and maintenance
Inspections during handover and acceptance: The operating mechanism, transmission device, auxiliary switch and locking device should be firmly installed, flexible and reliable in operation, and the position indication should be correct; the three-phase phase difference value should comply with the technical specifications of the product; the phase distance and the contact opening angle and distance when opening the switch should comply with the technical specifications of the product; the contacts should be in close contact; the paint should be complete, the phase color marking should be correct, and the grounding should be good.
2. Operation precautions
Check during operation: the insulator is intact, without cracks or discharge; the operating connecting rod and various mechanical parts are not damaged or rusted, the parts are tight and in the correct position, without abnormal phenomena such as skewness, looseness, and falling off; the locking device is in good condition, and the pins and auxiliary contacts of the electromagnetic group lock or mechanical lock of the disconnector should be in the correct position; the arc extinguishing angle of the blade and the knife mouth should not be burned, overheated, deformed, rusted, or tilted, the contact contact should be good, the joints and contacts should not be overheated, and the temperature should not exceed 70°C; the blade and the knife mouth should be free of dirt and burn marks, and the spring leaves, springs and copper braids should not be broken or broken: the grounding switch should be well grounded, especially the flexible parts that are easily damaged should be free of abnormalities.
3. Maintenance
(1) Check the open and closed positions of the circuit breaker before operation to prevent the disconnector from operating under load;
(2) Close the circuit breaker manually quickly and decisively without excessive force;
(3) Pull open the disconnector quickly to extinguish the isolation as soon as possible;
(4) If the disconnector is mistakenly closed under load, it is not allowed to be pulled open again;
If the disconnector is pulled by mistake, it should be closed immediately when the blade just leaves the fixed contact. If the disconnector blade has left the fixed contact, the mistaken disconnector must not be closed again
(5) After closing the circuit breaker, check whether the contact is tight; after pulling the circuit breaker, check whether each phase is in the disconnected position;
(6) After the operation is completed, lock the operating handle.
Difference from circuit breaker
| Features | Isolating switch | Circuit breaker |
|---|---|---|
| Function | Isolation circuit, no arc extinguishing capability | Cut off load current and fault current |
| Operation sequence | First turn off the circuit breaker, then operate the isolating switch | Directly disconnect load or fault current |
| Visible disconnection point | Yes | None (enclosed structure requires additional instructions) |
contact us
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