What control switches should be selected for low-voltage switchgear

As an important electrical equipment, switchgear is widely used. Almost any supermarket, factory, individual enterprise, etc. will use switchgear. How to choose the control switch for switchgear? Yubai New Electric specializes in producing various types of high and low voltage switchgear, distribution cabinets, and other electrical equipment. It is a professional enterprise that integrates the development, design, manufacturing, sales, and service of automation system control cabinets, providing users with one-stop services.

The selection of switches for switchgear

According to the functions of the distribution panel in the switchgear device, the control switches inside the panel should have the following functions:

(1) Can connect and disconnect the normal load current of the circuit;

(2) Can reliably break short-circuit current;

(3) Can clearly indicate the open or closed state of the circuit.

Switching devices with the above performance include knife melting switches and load switches, but knife melting switches are inferior to magnetic switches (contactors with thermal relays, also known as magnetic starters) and automatic circuit breakers in terms of their ability to protect electrical equipment and line overload, as well as their performance in the event of short circuit accidents. In terms of the ability of load switches to switch between normal load current and short-circuit current in the circuit, it is difficult to meet the needs of high-capacity power receiving equipment and low-voltage power grids with large short-circuit capacity. Automatic circuit breakers can not only protect the overload of power receiving equipment and lines, but also selectively and reliably disconnect short-circuit current in case of short-circuit accidents. However, the automatic circuit breaker does not have a clear indication function for the circuit breaking or closing status (i.e. the working status that can be seen by operators), so a set of knife switches should be added in front of the automatic circuit breaker (power side). This type of knife switch is not used for breaking and closing line currents, and is generally referred to as an isolation switch. Magnetic switches can protect electrical equipment and lines from overload, but in low-voltage power grids with large short-circuit capacity, the breaking capacity of magnetic switches is insufficient, and there is no obvious indication of the line breaking or closing status. Therefore, a set of knife melting switches should be added in front of the magnetic switch (power side), which not only serves as a clear breaking point but also has short-circuit protection function.

In summary, the control switches referred to above include not only knife melting switches and load switches, but also knife switches (isolating switches) combined with various automatic circuit breakers and magnetic switches, as well as knife switches and fuses with arc extinguishing covers.