What Is A High Voltage Disconnect Switch?
High Voltage Disconnect Switch is mainly used to reliably isolate the part of the high-voltage power distribution device that needs to be shut down from the live part to ensure the safety of maintenance work.
The contacts of the isolating switch are all exposed to the air and have obvious disconnection points. The isolating switch has no arc extinguishing device, so it cannot be used to cut off the load current or short-circuit current. In layman's terms, the isolating switch can only work when the high-voltage circuit breaker is disconnected. Otherwise, under the action of high voltage, a strong arc will be generated at the disconnection point, and it is difficult to extinguish itself. It may even cause arcing (relative to ground or phase-to-phase short circuit), burn equipment, and endanger personal safety. This is the so-called "load-pulling isolating switch" serious accident. The isolating switch can also be used to switch certain circuits to change the operating mode of the system.
What is a vacuum circuit breaker?
It is named because its arc extinguishing medium and the insulating medium of the contact gap after arc extinguishing are both high vacuum; it has the advantages of small size, light weight, suitable for frequent operation, and arc extinguishing without maintenance, and is widely used in distribution networks.
The vacuum circuit breaker is an indoor power distribution device in a 3-10kV, 50Hz three-phase AC system. It can be used for the protection and control of electrical equipment in industrial and mining enterprises, power plants, and substations. It is particularly suitable for use in places that require oil-free, less maintenance, and frequent operation. The circuit breaker can be configured in a central cabinet, a double-layer cabinet, or a fixed cabinet to control and protect high-voltage electrical equipment.
1. Working principle of vacuum circuit breaker
When the moving and static contacts are opened under the action of the operating mechanism, an arc is generated between the contacts, and the contact surface evaporates steam at high temperature. Since the contacts are designed in a special shape, a magnetic field is generated when current passes through. Under the action of this magnetic field, the arc moves rapidly along the tangent direction of the contact surface, and part of the metal vapor condenses on the metal cylinder (shielding cover). The arc is extinguished when it naturally crosses zero, and the dielectric strength between the contacts is quickly restored.
2. Function of vacuum circuit breaker
The circuit breaker has overload, short circuit and undervoltage protection functions, and has the ability to protect lines and power supplies.
The difference between the three
Isolating switch
Can only disconnect and connect the system no-load current, and as the main wiring system obvious disconnection point, as the system obvious disconnection point during maintenance.
Load switch
Can disconnect and connect the system normal load current, but cannot disconnect the system short-circuit current.
Circuit breaker
In addition to disconnecting and connecting the system normal load current, it can also disconnect and connect the system fault and short-circuit current.
