What is the disconnect switch?

Isolation switch (disconnector), that is, in the sub-position, there is an insulation distance that meets the specified requirements and an obvious disconnection mark between the contacts; in the closed position, it can carry the current under the normal loop condition and the abnormal condition within the specified time ( For example, the switching device of the current under short circuit. (IEV441-14-05).

Isolating switch (commonly known as "knife switch"), generally refers to a high-voltage isolating switch, that is, an isolating switch with a rated voltage of 1kV and above, usually referred to as an isolating switch, which is the most used electrical appliance among high-voltage switching appliances. The working principle and structure are relatively simple, but due to the large amount of use and high reliability requirements, it has a greater impact on the design, establishment and safe operation of substations and power plants. The main feature of the isolating switch is that it has no arc extinguishing ability and can only open and close the circuit when there is no load current. Isolating switch is used at various levels of voltage to change the circuit connection or isolate the circuit or equipment from the power supply. It has no current interruption capability and can only be operated after disconnecting the circuit with other equipment. Generally, it is equipped with an interlock device to prevent the switch from being operated incorrectly when the switch is under load. Sometimes a pin is needed to prevent the switch from being disconnected under the action of a large fault magnetic force.

• Feature

1）After opening, establish a reliable insulation gap, and separate the equipment or lines that need to be overhauled from the power supply with an obvious disconnection point to ensure the safety of overhaul personnel and equipment

2）According to operational needs, switch lines.

3） It can be used to divide and combine small currents in the circuit, such as the charging current of bushings, busbars, connectors, short cables, the capacitance current of the switch voltage equalizing capacitor, the circulating current when the double busbar is switched, and the excitation current of the voltage transformer Wait.

4)）According to the specific conditions of different structure types, it can be used to divide and combine the no-load excitation current of a certain capacity transformer.

According to different installation methods, high-voltage isolating switches can be divided into outdoor high-voltage isolating switches and indoor high-voltage isolating switches. Outdoor high-voltage isolating switch refers to a high-voltage isolating switch that can withstand the effects of wind, rain, snow, dirt, condensation, ice, and thick frost, and is suitable for installation on the terrace. According to the different insulation pillar structure, it can be divided into single-column disconnector, double-column disconnector, and three-column disconnector. Among them, the single-column knife switch directly uses the vertical space as the electrical insulation of the fracture under the overhead bus. Therefore, it has obvious advantages of saving floor space, reducing lead wires, and the opening and closing state is particularly clear. In the case of ultra-high voltage power transmission, the effect of saving floor space is more significant after the single-column knife switch is adopted in the substation.