Classification of high voltage circuit breakers and their role

Classification of high voltage circuit breakers

The types of high-voltage circuit breakers are complex and can be generally classified according to the following methods:

The circuit breaker can be divided into indoor type and outdoor type according to the installation location;

According to the circuit breaker arc-extinguishing principle or arc extinguishing medium can be divided into oil circuit breaker, vacuum circuit breaker, sulfur hexafluoride (SF6) circuit breaker, etc.

1.Oil circuit breaker

The circuit breaker with insulating oil as the extinguishing medium is called the oil circuit breaker. It can also be divided into multi - oil circuit breaker and less oil circuit breaker.

In addition to the use of insulating oil in the multi-oil circuit breaker as the arc extinguishing medium, but also as the main insulation between the contacts after the contact is disconnected and the main insulation between the live part and the earth shell. The multi-oil circuit breaker has the characteristics of large amount of oil, large amount of metal consumables, easy fire or explosion, large volume, processing technology requirements are not high, durable, low price.

At present, in the power system, except some outdoor multi-oil circuit breakers such as 35kV are still in use, the production and use of other multi-oil circuit breakers have been stopped.

The insulating oil in the low-oil circuit breaker is mainly used as the arc extinguishing medium, and the insulation between the live part and the ground mainly uses insulators or other organic insulating materials. This type of circuit breaker is called less oil circuit breaker because of less oil consumption.

The less oil circuit breaker has the advantages of less consumables and low price, but it needs regular maintenance and has the risk of fire and explosion. Less oil circuit breakers are currently in use, but they have been gradually replaced by vacuum circuit breakers and SF6 circuit breakers.

2.Vacuum circuit breaker

Vacuum circuit breaker is a circuit breaker that uses "vacuum" as insulating medium and arc extinguishing medium. The so-called "vacuum" here can be understood as a rarefied gas space where the pressure of the gas is much less than one atmosphere and there are very few gas molecules in the space.

Vacuum circuit breaker is a kind of circuit breaker made by installing its dynamic and static contacts in the "vacuum" sealed container (also known as the vacuum arc extinguishing chamber).

3.Hexafluoride (SF6) circuit breaker

Sulfur hexafluoride (SF6) circuit breaker is a circuit breaker that adopts SF6 gas with high quality insulation performance and arc extinguishing performance as the arc extinguishing medium. SF6 circuit breaker has the advantages of strong arc extinguishing performance, no spontaneous combustion and small size.

The effect of the high voltage circuit breaker

High-voltage circuit breakers play two roles in the power grid:

One is the control function, that is, according to the needs of the power grid operation, part of the electrical equipment or lines into or out of operation (open and close the normal working current);

The second is the protective effect, that is, when the electrical equipment or power line fault occurs, the relay protection or automatic device sends a trip signal, so that the circuit breaker is disconnected, the fault equipment or line from the grid quickly cut out, to ensure the normal operation of the fault-free part of the grid (disconnect short circuit current).

In the power system, the high-voltage circuit breaker can cut off and connect the no-load current and load current in the high-voltage circuit, but also can cooperate with the protection device and automatic device in the case of system failure, quickly cut off the fault current, prevent the expansion of the accident, ensure the safe operation of the system.

The advantage of the high voltage vacuum circuit breaker

High voltage vacuum circuit breaker is suitable for 10-35kv, single three-phase power system, as dividing and combining load current, overload current and short circuit current. The overall structure is porcelain bottle pillar type, the upper porcelain bottle is arc extinguishing chamber porcelain bottle, the inner is filled with straight empty arc extinguishing chamber, and the lower porcelain bottle is pillar porcelain bottle.

The three-phase porcelain bottle is installed on a mechanism, and a new type of insulation material is used to fill the space between the arc extinguishing chamber and the porcelain bottle, which not only plays the role of insulation but also solves the problem of condensation. The insulation has the characteristics of good insulation performance and high temperature resistance.

The disadvantage of high voltage vacuum circuit breaker is high one-time investment and high maintenance cost.

And its advantages are as follows.

(1) Simple structure, less maintenance and overhaul workload.

(2) Long service life and reliable operation.

(3) can operate frequently, no noise.

(4) The vacuum arc extinguishing effect is good, the arc is not exposed.

(5) No explosion risk. It is widely used.