Functions of Electrical Switchgear and Switchboard Systems

In most industrial and commercial applications the continuity and distribution of electrical energy is extremely important regarding not only the efficiency of the facility, but also the safety of the personnel involved. Generally, within an installation, power distribution and protection concerning equipment is carried out by either switchgear or board version devices.

A Comparison of Switchgear and Switchboard Devices

Switchgear devices are basically mechanisms consisting of: fuses, circuit breakers and electrical relays, which are utilized to connect or disconnect the flow of electrical energy. As switchboards consist of basically the same mechanisms as switchgear systems they are consequently said to be a type of switchgear apparatus. A more precise outline of a switchgear system is however, given by the United States National Electrical Code: “A large single panel, structural frame or assembly of panels or structural frames, on which switches, protective devices, buses and instruments may be mounted”.

Although switchgear and switchboard devices seem similar in function, one of the main differences between these mechanisms is the allowable voltage. Switchgear systems can generally deal with voltages of up to 35000 volts, whilst switchboards, are typically used in commercial applications when energy levels under 600 volts are concerned.

Major hardware property differences consequently exist in order to allow for the higher voltage levels in switchgear systems opposed to switchboard systems. The first of these differences can be seen regarding the types of Circuit Breakers that are utilized. In switchgear systems ‘power circuit breakers’ can be used, these breakers allow for high voltages to be utilized, as well as enabling breakers and other parts to be withdrawn or replaced while the system is still live.

switchboards in comparison generally utilize ‘molded case circuit breakers’, these breakers are usually only able to handle low voltages, and if a failure occurs, the entire system must be shut down in order for components to be repaired or replaced. This is extremely problematic within a system that requires continuous electrical energy to function. To combat this in some situations facilities may use ‘insulated case breakers’, although these breakers can only be utilized in a rear-accessible switchboards, they do allow for some maintenance while the system is live.

The in-facility size requirements regarding switchgear and switchboard systems are quite similar. Some authors however, argued that when a front accessible board is utilized the space saved can be quite substantial as it can be located against a wall. As previously stated however, ‘insulated case breakers’ can only be used in rear-accessible systems, meaning that although front-accessible switchboards may save space, they require repair downtime.

One may wonder, with all of the seemingly negative points standing against switchboards in comparison to switchgear systems, why installations would choose to use them at all. The answer to this question in most cases is the extremely high cost of switchgear systems when compared to switchboards. Some experts put the price of switchgear systems at two to three times that of switchboard devices.

In conclusion it can be seen that switchgear systems may be more reliable and robust constructions however, in many cases such technology is not affordable. Ever advancing technology regarding components such as circuit breakers however, are giving facilities more and more technical options to choose from, and enabling them to develop better energy management systems.