Do you really understand changeover switches? –AISO

What is an isolating switch

 The isolating switch, also known as the knife switch, is a kind of high-voltage switch. It has no arc extinguishing device. When it is in the closed position, it can carry the working current, but it cannot be used to connect or cut off the load current and short-circuit current. Should cooperate with circuit breaker.

2. The purpose of isolating switch

 2.1 Isolation voltage: During maintenance, the electrical equipment is isolated from the running power grid with an isolating switch to form an obvious disconnection gap, so as to ensure the safety of operation and maintenance.

2.2 Shutdown operation: switch on the backup bus or bypass bus and change the operation mode, use the isolating switch and the circuit breaker to complete.

 In the double busbar connection mode, the connection element is switched between the two busbars by using the on-off of the isolating switch position on the two busbars.

 2.3 Turning on and off the small current circuit: The isolating switch has a certain ability to turn on and off small inductive current and capacitive current. The isolating switch can be used for the following operations during operation:

 ①. Can be used to connect and disconnect voltage transformers and arresters.

 ②. Connect and disconnect no-load transmission lines with a capacitance current not exceeding 5A, a voltage of 10kV, and a no-load transmission line with a length of less than 5km and a no-load transmission line with a voltage of 35kV and a length of less than 10km.

 ③. Turn on and off the no-load transformer whose excitation current does not exceed 2A: the 35kV class is less than 1000kVA, and the 110kV class is less than 3200kVA.

 2.4 Automatic and rapid isolation: Under certain conditions, it can quickly isolate the equipment and lines that have failed to achieve the purpose of saving the amount of circuit breakers.

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