When it comes to high voltage electrical equipment, circuit breakers play an important role in protecting the system from short circuits and overloads. In this article, we’ll take a closer look at two types of circuit breakers: SF6 circuit breakers and vacuum circuit breakers.

To start with, circuit breakers are generally used in places where frequent disconnections are needed, while load switches are typically used in places where disconnection is not needed often. However, when it comes to high voltage systems, load switches alone are not sufficient to protect the system from short circuits and overloads. That’s where circuit breakers come in.

There are different types of circuit breakers available, including  high voltage load switches , high voltage circuit breakers, and  high voltage fuses. High voltage load switches are equipped with simple arc-extinguishing devices, which can make and break certain load currents and overload currents, but they cannot interrupt short-circuit currents. Therefore, they must be used in conjunction with high-voltage fuses to remove short-circuit faults.

On the other hand, high voltage circuit breakers have a sophisticated arc extinguishing system that enables them to make and break both normal load currents and certain short-circuit currents. In addition, they can automatically trip under the action of protective relays to remove short-circuit faults. High voltage circuit breakers are classified according to the arc extinguishing medium they use, including oil circuit breakers, SF6 circuit breakers, and vacuum circuit breakers.

Let’s take a closer look at SF6 circuit breakers. These breakers are characterized by their high dielectric strength, which allows them to use fewer breaking elements than air or oil circuit breakers. For example, a 220kV SF6 circuit breaker only requires one or two breaking elements, while an air or oil circuit breaker would require four breaking elements for the same rated voltage level.

In addition, SF6 circuit breakers allow for a greater number of operations and longer maintenance intervals compared to other  circuit breaker types. This is because SF6 gas can be restored after it is decomposed, and the decomposition products generated during the arc are not harmful to the insulating ability of the gas. Moreover, when water content is strictly controlled, the decomposition products generated during the arc do not have corrosive effects on the circuit breaker, so the insulation strength of the gas does not decrease after breaking. As a result, the maintenance intervals of SF6 circuit breakers are longer.

Another advantage of SF6 circuit breakers is their superior breaking performance. They allow for high currents to be interrupted quickly and efficiently, regardless of whether the current is large or small. This is due to the short arcing time and high dielectric strength of SF6 gas.

Moreover, SF6 circuit breakers have a high current-carrying capacity because SF6 gas has a high thermal conductivity and cools the contacts and conductors effectively. Since there is no oxygen in SF6 gas, there is no oxidation problem even at high temperatures.

Lastly, SF6  circuit breakers are often used in fully enclosed system structures, which take up less space and offer superior pollution resistance.

In summary, SF6 circuit breakers and vacuum circuit breakers both offer advantages and disadvantages. While SF6 circuit breakers are efficient, have good breaking performance, and are easy to maintain, vacuum circuit breakers are often preferred for their simplicity, low maintenance, and environmental friendliness. It’s important to carefully consider the specific application and requirements when choosing between these two types of circuit breakers.