The main function of the electrical isolation switch is to isolate the power supply and switch circuit, so that the equipment and power supply has a clear disconnect point to ensure the safety of maintenance personnel. No special arc device, can only turn off the smaller current, and can not break the load current, but can not break short-circuit current, with a clear break point, there is sufficient insulation to protect the safety of the person and equipment The
1. To isolate power supply. In the outage and maintenance of electrical equipment, use the electrical isolation switch to isolate the equipment need power outage and maintenance with power supply, to form a clear visible disconnect point to ensure the safety of staff and equipment.
2. Switching operation. The running state of electric equipment can be divided into three working states: running, standby and overhauling. The operation of changing the electrical equipment from one working state to another is called a switching operation. For example, in a circuit with double busbar connection, the power supply line can be switched from one set of bus power supply to another busbar without disrupting the user power supply condition by using an isolating switch (called busbar electrical isolation switch) connected to the busbar.
3. Open, close no current or low current circuit. High voltage isolation switch Although there is no special arc extinguishing equipment, but in the process of pulling the small current can be cut off, due to dynamic and static contact quickly opened, according to the rapid elongation of the arc Arc off principle, you can make the contact between the arc off. Therefore, the high voltage isolating switch allows the following circuits to be pulled:
(1) Open, close circuit of voltage transformer and arrester circuit;
(2) Open, close the bus and the capacitor current directly connected with the bus;
(3) Open, close the no-load transformer with excitation current less than 2A : the general voltage of 35kV, the capacity of 1000kVA and below the transformer; voltage 110kV capacity of 3200kVA and below the transformer.
(4) Open, close the no-load current of no more than 5A: the general voltage of 10kV, the length of 5km and below the overhead lines; voltage 35kV, the length of 10km and below the overhead lines.
In summary: the role of the electrical isolation switch is to disconnect the no-load current circuit, so that the equipment and power supply has a clear disconnect point to ensure the safety of maintenance personnel, isolation switch without a special arc device can not cut off the load Current and short-circuit current, it is necessary to operate the electrical isolation switch in the circuit when the circuit breaker is disconnected from the circuit.