What is a Load Switch? What is an Isolating Switch? What is a Vacuum Circuit Breaker?

What is a load switch?

It is a control electrical appliance with a simple arc extinguishing device that can divide and close the circuit with load. It can turn on and off a certain load current and overload current, but cannot disconnect the short-circuit current. It must be used in series with a high-voltage fuse, and the short-circuit current can be cut off with the help of the fuse.

The role of load switch:

1. Switching and closing functions. Because it has a certain arc extinguishing ability, it can be used to break and close the load current and a certain multiple (usually 3-4 times) overload current.

It can also be used to break and close the Larger no-Larger-load transformers and longer no-load lines which capacity larger more than isolate swichgear.sometimes it aslo used to open and close large-capacity capacitor banks.

2.Substitution effect

The series combination of load switch and current limiting fuse can be used instead of circuit breaker. That is, the load switch is responsible for breaking and closing the overload current less than a certain multiple, and the current limiting fuse is responsible for breaking the larger overload current and short-circuit current.

3.The load switch is a load switch that is combined in series with the current limiting fuse. It is stipulated in the national standard that it is called "load switch-fuse combination". The fuse can be installed on the power supply side of the load switch or on the load switch. the power receiving side. When the fuse does not need to be changed frequently, the former arrangement should be adopted, so that the load switch can be used as the isolating switch to isolate the voltage applied to the current-limiting fuse.

What is an isolation switch?

It is a control electrical appliance without an arc extinguishing device. Its main function is to isolate the power supply to ensure the safe maintenance of other electrical equipment, so it is not allowed to operate with load. However, under certain conditions, it is allowed to connect or disconnect low-power circuits. It is one of the most frequently used electrical devices in high-voltage switches.

The role of the isolation switch:

1. After opening, establish a reliable insulation gap, and separate the equipment or line that needs to be repaired from the power supply with an obvious disconnection point to ensure the safety of maintenance personnel and equipment.

2. According to the operation needs, change the line.

3. It can be used to divide and combine small currents in lines, such as bushings, busbars, connectors, charging currents of short cables, capacitive currents of switch grading capacitors, circulating currents when double busbars are switched, and excitation currents of voltage transformers 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.

High voltage isolation switches can be divided into outdoor high voltage isolation switches and indoor high voltage isolation switches according to their different installation methods.

Outdoor high-voltage isolating switch refers to a high-voltage isolating switch that can withstand the effects of rain, snow, dirt, condensation, ice and thick frost, and is suitable for installation on terraces.

According to the structure of its insulating pillars, it can be divided into single-column isolating switch, double-column isolating switch, and three-column isolating switch. Among them, the single-column isolating switch directly uses the vertical space as the electrical insulation of the fracture under the overhead busbar. Therefore, it has the obvious advantages of saving the floor space and reducing the lead wires. In the case of power transmission, after the substation adopts the single-column isolating switch, the effect of saving land and space is more significant.

In low-voltage equipment, isolating switches are mainly suitable for low-voltage terminal distribution systems such as residential buildings and buildings. Main functions: with load breaking and connecting lines.

What is a vacuum circuit breaker?

It is named because the arc extinguishing medium and the insulating medium of the contact gap after arc extinguishing are high vacuum; it has the advantages of small size, light weight, suitable for frequent operation, and no need for maintenance for arc extinguishing. universal.

The direct-air circuit breaker is an indoor power distribution device in a 3~10kV.50Hz three-phase AC system. It can be used for protection and control of electrical equipment in industrial and mining enterprises, power plants and substations. It is especially suitable for oil-free, For places with less maintenance and frequent operations, circuit breakers can be configured in central cabinets, double-layer cabinets, and fixed cabinets 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 surface of the contacts volatilizes steam at high temperature. Due to the special shape of the contacts, a magnetic field is generated when the current passes through, and the arc is in the Under the action of this magnetic field, it moves rapidly along the tangential direction of the contact surface.Part of the metal vapor is condensed on the metal cylinder (shielding cover), and the arc is extinguished when it naturally crosses zero, and the dielectric strength between the contacts quickly recovers.

2. The role of vacuum circuit breaker

The circuit breaker has overload, short circuit and undervoltage protection functions, and has the ability to protect the line and the source.