An Introduction To Switchboards

What Is the Purpose of an Electrical Switchboard?

Switchboards ensure that electricity is distributed securely across commercial and industrial buildings. A switchboard is an electrical distribution system component that separates an electrical power feed into branch circuits while also providing each circuit with a protective circuit breaker or fuse in a single enclosure.

Switchboards are normally intended to meet UL891 and NEMA Standard PB2 and have a maximum voltage rating of 600 Vac/Vdc and a maximum bus rating of 6000 A.

What Is the Distinction Between Panelboards and Switchboards?

In a power distribution system, switchboards and panelboards perform similar functions. Panelboards, whether flush mounted within a wall or surface affixed to a wall, are normally limited to 1200 A incoming current (main). Switchboards, like panelboards, are freestanding machines that can be front linked and require just front access.

On the other hand, Switchboards can provide access from both the front and the back if required. Up to 6000 A of bussing and overcurrent devices can be found in switchboards. UL 67 applies to panelboards, while UL 891 applies to switchboards.

Structures of Switchboards

Depending on the number and size of the loads to be powered, a switchboard is made up of a single vertical structure or many structures.

The main disconnects or main lugs are located in the main structure, which also houses utility and customer metering equipment and surge protection.

Cabling might enter the main structure directly or through a separate pull structure. In service entry switchboards, pull structures are often employed. Cables can enter the structure from both the bottom (bottom entry) and the top (top entry) (top entry.)

Power is divided and sent to branch circuit protection devices before being sent to branch circuits to downstream power loads. The cross bus transports power from the main structure to the distribution structure.

Types of Switchboards

Switchboards come in a variety of shapes and sizes.

Switchboards for General Use

Integrated insulated case circuit breakers, moulded case circuit breakers, fused switches, metering, and surge protection can all be found in general-purpose switchboards. A general-purpose switchboard may handle the vast majority of switchboard applications.

Fusible Switchboards

Fusible switchboards are used to safeguard and switch feeder and branch circuits in commercial, industrial, and service entrance applications. A switching contact structure with an instantaneous trip element is included in each panelboard unit.

Switchboards for Commercial Metering

Circuit breakers, chassis, surge protection, and metre sockets are included in a single, engineered assembly in commercial metering switchboards. The utility may demand bulb-type watt-hour metres or electronic tenant metering for metering.

Switchboards With a Pull-out Moulded Case

Draw-out moulded case switchboards have the same fundamental characteristics as a general-purpose switchboard, but they also can draw out one or more feeder breakers. To avoid system downtime when replacing a breaker, draw-out moulded case switchboards are commonly used in sensitive applications such as healthcare and data centres.

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