Difference Between Switchgear and Switchboard: You Must Know

In the world of electrical systems, two terms that often come up are switchgear and switchboard. While they may sound similar, they serve distinct functions and have unique characteristics. Understanding these differences is crucial for anyone involved in electrical engineering, maintenance, or operations.

In this comprehensive guide, we will delve into the key distinctions between switchgear and switchboards, their functions, applications, and importance.

What is Switchgear?

Switchgear refers to the combination of electrical disconnect switches, fuses, or circuit breakers used to control, protect, and isolate electrical equipment. It is used in both high voltage and low voltage power systems.

The primary function of switchgear is to ensure the safe and reliable operation of electrical power systems by interrupting fault currents and protecting the system from overloads and short circuits.

What is Switcboard?

A switchboard is an assembly of one or more panels, each of which contains switches, breakers, and fuses. It is designed to control the distribution of electrical power to different circuits and equipment.

Switchboards are typically used in low voltage applications and are a central point where power is distributed to various loads.

Know More about Switcgear and Switcboard

Low voltage switchgear and low voltage switchboards are products used to safely distribute power throughout a facility.

Both assemblies use free-standing enclosures that house circuit breakers, bus bars, and power cables. Both products can contain meters, relays, potential transformers, current transformers, and transfer schemes for redundant power. However, that's where the differences lie.

Switchboards are typically built with a dead-front, open-chassis design with little or no internal barriers between cables, circuit breakers, and bus bars. When the dead-front switchboard is removed, all bus bars, cables, and terminations are exposed.

Switchboards are tested according to UL 891 Switchboard standards and typically consist of molded case circuit breakers (MCCB) mounted in a fixed position that complies with UL 489 MCCB standards. Switchboards tend to be front accessible, meaning incoming and outgoing cable terminations are accessible from the front, allowing the assembly to be wall-mounted.

This difference results in a smaller footprint compared to similar switchgear assemblies containing the same number of circuit breakers.

Switchboards also tend to be cheaper than switchgear. For example, fixed-mounted MCCBs are less expensive than draw-out MCCBs.

However, MCCBs are not designed to be serviced, and if the breaker is fixed-mounted, the switchboard must be de-energized to replace it.

Switchgear, on the other hand, contains draw-out power circuit breakers (draw-out MCCBs) that can be removed from the equipment while energized and are designed to be fully serviceable.

Switchboards only have a short-time current withstand rating of 3 cycles, compared to the 30-cycle rating of switchgear.

This is due to MCCBs only having a 3-cycle short-time current withstand rating. This means achieving selective coordination is more challenging because short-time delays cannot be programmed to allow downstream circuit breakers time to clear the fault.

Certain arc-flash safety technologies are also not available in switchboards. These technologies are only available in low voltage switchgear, including Arc Quenching technology and arc-resistant construction.

In facilities that consume large amounts of power and require reliable power, both switchgear and switchboards play important roles.

Switchgear can provide primary low voltage power distribution and protection, often located at the incoming or secondary transformer substation, distributing power to various low voltage switchboards and MCCs located throughout the facility, which in turn distribute power to smaller branch circuits such as lighting, HVAC, and process-specific loads.

Major Differences Between Switchgear and Switchboard

1. Function and Application

Switchgear: Used for both high and low voltage applications, switchgear is primarily focused on protection, control, and isolation of electrical equipment. It is commonly found in power generation plants, substations, and industrial facilities.

Switchboard: Mainly used for low voltage applications, a switchboard's primary function is the distribution of electrical power to various circuits and loads. It is typically found in commercial buildings, residential complexes, and smaller industrial facilities.

2. Voltage Levels

Switchgear: Can handle both high and low voltage levels, typically above 36 kV for high voltage switchgear.

Switchboard: Primarily designed for low voltage applications, usually below 600 V.

3. Components

Switchgear: Includes circuit breakers, disconnectors, fuses, and relays, all designed for protection and control.

Switchboard: Consists of busbars, circuit breakers, switches, and monitoring instruments for power distribution.

4. Protection Capabilities

Switchgear: Offers extensive protection capabilities, including fault detection, interruption, and isolation. It is equipped with advanced protective devices like relays and circuit breakers that can detect and clear faults quickly.

Switchboard: Provides basic protection for individual circuits through the use of circuit breakers and fuses but does not have the advanced protective features found in switchgear.

5. Complexity and Cost

Switchgear: More complex and expensive due to its advanced protection and control features. It requires specialized knowledge for installation, operation, and maintenance.

Switchboard: Simpler and less expensive compared to switchgear. It is easier to install and maintain, making it suitable for less complex electrical systems.

Applications of Switchgear and Switchboard

Switchgear

• Power Generation Plants: Ensures the protection and control of electrical equipment in power generation plants.

• Substations: Used in substations to control the flow of electricity and protect the electrical network from faults.

• Industrial Facilities: Protects and controls electrical equipment in industrial facilities, ensuring safe and reliable operation.

Switchboard

• Commercial Buildings: Distributes power to various circuits and loads in commercial buildings.

• Residential Complexes: Ensures safe distribution of power to individual units in residential complexes.

• Small Industrial Facilities: Controls and distributes power to various loads in small industrial facilities.

Conclusion

Switchgear and switchboard are both essential components of electrical systems, each serving distinct functions and applications. While switchgear focuses on protection, control, and isolation in both high and low voltage applications, switchboard primarily deals with the distribution of power in low voltage systems.

Understanding the differences between these two components is crucial for the safe and efficient operation of electrical systems.