Fundamentals of Electrical Switchgear: How it Works, Types, and Components

Switchgear is a crucial part of electrical power systems, used to control, protect, and isolate electrical equipment. It ensures safe power distribution by detecting faults and interrupting current flow, helping maintain system stability and safety across residential, commercial, and industrial applications.

How Electrical Switchgear Works

Switchgear works by isolating specific components for maintenance or repair. It controls the flow of electrical power through fault interrupters, circuit breakers and switching devices. When a fault is detected, the switchgear quickly isolates the issue while keeping the rest of the system energized.  Once the issue is resolved, circuits can be safely re-energized. Safety features are crucial to switchgear functionality, with overcurrent protection playing a vital role in preventing damage from excessive current flow in a circuit.

What are Types of Electrical Switchgear?

There are three main types of electrical switchgear: low-voltage (LV), medium-voltage (MV), and high-voltage (HV).

Low Voltage (LV) Switchgear

Low-voltage switchgear is a common type of electrical switchgear used in various industries to regulate systems up to 1kV. It is commonly found in residential, commercial, and industrial settings where voltage is low.

Medium Voltage (MV) Switchgear

Medium voltage (MV) switchgear operates in systems with voltages from 1kV up to 35kV. Typically employed in utility distribution, data centers, hospitals and other commercial and industrial applications providing enhanced protection and control for medium-voltage electrical switchgear systems.

High Voltage (HV) Switchgear

High Voltage (HV) switchgear is designed to handle voltages above 35kV. Often associated with power transmission networks, it finds application in large-scale industrial plants. HV switchgear plays a pivotal role in ensuring the safe and reliable transfer of electricity over long distances.

Types of Switchgear by Insulation: AIS, GIS, OIS & Vacuum

Switchgear uses various types of insulation to protect operators from electrical shock and create a barrier between energized components. Below are the different types of insulation.

Air Insulated Switchgear

Air insulated switchgear (AIS) is the most common and most cost-effective insulation option. Its design and operation are relatively simple, and it’s known for being environmentally friendly. However, AIS does has some drawbacks, such as low dielectric strength, which makes it a relatively poor insulator, requiring larger equipment, which can be a disadvantage in applications where space is limited, particularly in low- and medium-voltage switchgear.

Gas Insulated Switchgear

Gas insulated switchgear (GIS) uses sulfur hexafluoride (SF6) as the insulation medium and as the interrupting medium load break operators and in some instances for fault interruption. GIS provides higher dielectric strength than AIS and has a more compact design. It’s ideal for harsh environments where submersible operation is required.

Oil Insulated Switchgear

Oil insulated switchgear (OIS) is commonly used for high-voltage applications in electrical power systems. In OIS, mineral oil is frequently used as an insulating and cooling medium. OIS offers high dielectric strength and can provide increased cooling benefits. However, a drawback of OIS is the potential environmental hazard and fire risk associated with oil leakage.

Vacuum Insulated Switchgear

Vacuum insulated switchgear uses vacuum interrupters for circuit breaking. It is commonly used in medium to high voltage applications. Some advantages of vacuum insulated switchgear include its high dielectric strength, reliability, low maintenance, and compact design.

Key Components of Electrical Switchgear Systems

Switchgear is constructed with diverse interconnecting components that vary depending on the specific application. Below are the main components involved in the switchgear system.

Circuit Breakers

Circuit breakers are essential for protecting electrical systems from overloads, short circuits, and faults. They work by interrupting the electrical current when a fault or overcurrent occurs. The primary function of circuit breakers is to ensure the safety and reliability of the entire electrical network. Circuit breakers are an essential part of any switchgear system.

Fault Interrupters

Fault interrupters are self-controlled mechanical devices that can make, carry, and switch continuous current. They can also detect and automatically interrupt fault currents without the ability to reclose automatically. These devices include a set of control elements that detect overcurrents and manage the fault interrupter.

Disconnect Switches

The primary function of disconnect switches is to allow for safe maintenance or repairs on isolated equipment. These switches work by physically disconnecting electrical equipment from the power supply, providing a crucial safety measure during maintenance activities.

Fuses

Fuses serve as protective devices that safeguard electrical circuits and equipment from overcurrent conditions. Their primary function is to interrupt the electrical current when it exceeds a predetermined level.

Relays

Relays serve as monitors and controllers of the electrical parameters within the system. Their critical role lies in the protection and automation in electrical switchgear systems, ensuring a swift response to abnormal conditions and maintaining the overall integrity of the electrical network.

Control Panels

Control panels serve as the central command and monitoring hub for electrical circuits and equipment. They provide operators with the tools to manage and motor various functions. They consist of various control devices, indicating lamps, and monitoring equipment, essential for the operation and supervision of the switchgear.

Visit our product page and learn more about G&W Electric’s switchgear.

FAQs