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What Is a Switchgear?

It’s no secret that a power surge can wreak havoc with your electrical systems. Circuits are designed to handle a limited amount of electricity, and when too much current passes through, it can cause the wiring to overheat. This may damage vital electrical components, or even lead to fires. Switchgears are designed to defend equipment connected to a power supply from the threat of electrical overload.

Switchgear Definition

What is a switchgear? Switchgear is a broad term that describes a wide variety of switching devices that all fulfill a common need: controlling, protecting, and isolating power systems. Although this definition may be extended to include devices to regulate and meter a power system, circuit breakers, and similar technology.

In the event of an electrical surge, an effective switchgear will trigger, automatically interrupting the flow of power and protecting the electrical systems from damage. Switchgears are also used for de-energizing equipment for safe testing, maintenance, and fault clearing.

Switchgear Examples
As stated, the term switchgear may refer to a number of different systems and components. Switchgear examples include the following:

• Switches
• Fuses
• Isolators
• Relays
• Circuit Breakers
• Lightning Arresters

Switchgear types
There are three different classes of switchgear systems: low-voltage, medium-voltage, and high-voltage. To determine which switchgear system is right for you match the design voltage of any system to the voltage rating of the switchgear.

High-Voltage Switchgears
High-voltage switchgears are those that control 75KV of power or more. Because these breakers are designed for high-voltage use, they often include improved safety features.

Medium-Voltage Switchgear
Medium-voltage switchgear are used in systems from 1KV up to 75KV. This switchgear is often found in systems involving motors, feeder circuits, generators, and transmission and distribution lines.

Low-Voltage Switchgear
Low-voltage switchgear are designed to regulate systems of up to 1KV. These are commonly found on the low-voltage sides of power-distribution transformers and are used across a variety of industries.

Isolating Media
In addition to the different voltage levels, switchgear may also be defined by the isolating media each uses to protect energized devices from electrical faults. The switchgear enclosure may make use of various insulators with different dielectric properties or other characteristics.

Although the least expensive insulation option (and thus the most commonly used), the air has a low dielectric strength, making it a relatively poor insulator. As a result, air-insulated devices are typically larger than devices insulated by other media.

Fluid offers better insulation when compared to air, and is similarly inexpensive. Fluid also provides the added advantage of cooling for overheated systems.

Pressurized gas also offers increased dielectric strength compared to standard air insulation. Although Sulfur Hexafluoride is a common insulating gas for switchgear systems, other gases may be used in its place.

Oil has a high dielectric strength, and may also provide increased cooling benefits.

Although less common and more expensive than some other options, solid, non-conductive materials can provide exceptional dielectric strength, as well as resistance to chemical and thermal deterioration.

Switchgear vs. Switchboard

The term “switchboard” is sometimes used synonymously with “switchgear.” However, these two devices have different primary functions.

Where a switchgear exists to connect and isolate load equipment to and from power sources, switchboards are used to direct the flow of electricity in a power distribution system.

How Does a Switchgear Work?

Different kinds of switchgears may follow different operational processes. That said, basic switchgears follow a relatively straightforward process:

In the event of an electrical fault, the relay closes the trip circuit, disconnecting downstream loads. This allows the remainder of a circuit to continue operating without disruption, while also protecting vital equipment from damage.

Switchgear Solutions from ASCO

The right switchgear can mean the difference between full operation and complete electrical system failure. ASCO offers a wide range of parallelling switchgear solutions that connect multiple power sources to backup power systems to provide the highest levels of reliability and availability to mission-critical facilities. Click here to learn more.

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