A Guide to Electrical Switchgear
Updated: May 4
What is electrical switchgear?
Electrical switchgear describes the various components of an electric power system that protect, control, and isolate circuits to prevent current overload. The components of switchgear include:
To prevent overload and short circuits, electrical switchgear transfers the load from one circuit to another. In the event of a faulty circuit, a relay and circuit breaker disconnect it from the power supply while ensuring an uninterrupted power supply to the load.
The market for electrical switchgear is growing rapidly due to the increased adoption of renewable energy sources, especially in rural areas, and the need for secure energy distribution. The Asia Pacific region is leading the way in electrification investment, further driving the growth of the switchgear market. With a market size of just over $105 billion in 2019, the global switchgear market is projected to grow at a CAGR of 6.6% and reach a market size of $170 billion by 2027.
What is switchgear used for?
Electrical switchgear is responsible for several actions and events that occur within an electrical system and plays a critical role in protecting, controlling, and isolating circuits within an electrical system.
Protect: Short circuits and current overloads can seriously damage equipment, cause fires in control panels, and threaten operator and public safety. Electrical switchgear interrupts the flow of excess current, effectively safeguarding against these risks.
Control: Modern electrical switchgear, equipped with IoT monitors, can relay comprehensive information about the status of an electrical system to a remote monitoring station. This allows for specific actions, such as the controlled depowering of equipment for maintenance or repair.
Isolate: Switchgear allows an electrical system to remove malfunctioning circuits from a system through circuit breakers and disconnectors. This can be done automatically or through the control of an operator.
Types of switchgear
There are several types of switchgear, each designed to handle different voltage levels and load capacities. Following the rated load capacity of a given electrical switchgear assembly is critical for the safety of operators and equipment.
The three categories offered by electrical switchgear manufacturers are:
Low voltage switchgear
Medium voltage switchgear
High voltage switchgear
Low-voltage electrical switchgear is designed to handle electrical systems up to 1kV and is typically found at the low-voltage end of a system, serving relatively smaller electrical equipment inside a building. They will commonly feature low-voltage switches, earth leakage circuit breakers, electrical isolators, and various circuit breakers that protect equipment and operators from thermal, mechanical, and electrical risks.
Many low-voltage switchgear systems will also have control panels or remote monitoring to allow for greater visibility of the electrical system. Some common examples of low-voltage switchgear are UL1558 standard (up to 600V) and UL891 standard (up to 1kV).
Medium-voltage electrical switchgear is designed to protect and control power systems with loads between 1kV and 36kV. Components of medium-voltage switchgear are generally contained in metal-enclosed structures and include sufficiently rated circuit breakers, fuses, transformers, and relays.
Medium-voltage systems are usually used in commercial and light industrial locations, as well as civic campuses like hospitals or universities. Different types of medium-voltage switchgear include:
Compact switchgear is designed for medium-voltage systems and contains sealed circuit breakers and disconnects in a metal-enclosed panel. It is designed to meet relevant regulations such as IEEE C37.20.9. Compact switchgear solutions are best suited for spaces with low accessibility or limited space and will often use gas-insulated switchgear (GIS).
In metal-clad electrical switchgear, the various components, such as switches, circuit breakers, transformers, and busbars, are housed in separate metal compartments. Metal-clad switchgear is commonly found in industrial plants and power generation and transmission facilities of utilities rated up to 36kV. Metal-clad switchgear protects components from environmental hazards and helps to prevent arc flash from endangering operators or equipment.
Metal-enclosed switchgear is typically used in commercial and industrial applications from 2.4kV to 36kV, particularly those not involved in high-cycle operations. Unlike metal-clad switchgear, the components of metal-enclosed switchgear, such as fuses, switches, and circuit breakers, do not require separate compartments and can be mounted together. The switchgear protects operators and equipment from arc flash and faults, while also allowing for safe and effective switching mechanisms.
Pad-mounted switchgear are specifically designed for outdoor applications and are commonly mounted on a concrete plinth or “pad”. This type of switchgear is commonly used by utilities and can also be found in industrial environments. Due to the specific needs of its applications, pad-mounted switchgear is outdoor-rated and has design features to make it tamper and weather-resistant. The construction and components of pad-mounted switchgear, such as oil switches, allows for sectionalizing as well as circuit protection, giving greater control over distribution.
This is typically used for underground installations, including electrical distribution for utilities and the incoming transformer substations for large industrial complexes. Understandably, subsurface electrical switchgear must be designed to consider certain conditions, such as temperature and potential water ingress. It incorporates components that assist electrical distribution and control, such as circuit breakers, relays, transformers, and sensors. It must also either be accessible for operators or allow them to operate switches from above ground.
High-voltage switchgear is specifically designed for distribution systems rated at over 36kV AC. A high-voltage system can be more efficient as it requires less current to transmit the same amount of energy. High-voltage switchgear and electrical systems are generally only used at utility substations or large industrial or health/education campuses.
Due to the risk to human life and equipment associated with systems such as three-phase power transmission, high-voltage electric switchgear must incorporate high-voltage fuses and high-current switching mechanisms to enable control over power being transmitted. This enables operators to manage the electricity flow safely and more efficiently.
Depending on its particular function in an electrical system, electrical switchgear may feature a variety of different components. Some, like circuit breakers, relays, and fuses, are considered core elements.
The most common electrical switchgear components are:
Circuit breakers: A circuit breaker protects equipment from short circuits by breaking the contact of the circuit when it detects a fault. The fault is detected by heat or magnetism and can be done within the apparatus. Compressed air or a spring will push the contacts apart if a fault is detected.
Instrument transformers: These components step down the high voltage and current from the distribution and transmission systems to lower values so that other equipment can use it or act as a protective relay preventing current overload.
Medium-voltage contractors: Medium-voltage contactors help protect equipment and control loads. They will typically consist of three vacuum interrupters housed in ceramic. If a short circuit occurs, the mechanism holding the contacts together moves them apart.
Medium-voltage fuses: These are the different kinds of medium-voltage fuses used in electrical switchgear assemblies, including high break, current limiting, and striker fuses, with ratings from 1kV to 36kV.
Smart monitoring: IoT sensors feed data about the status of the particular electrical switchgear and the overall electrical system to monitoring applications. These sensors can withstand difficult conditions and allow for remote system oversight, improving safety and efficiency.
Switches and disconnectors: Switches in electrical switchgear are used for making, breaking, or carrying current. Disconnectors are either ‘on’ or ‘off’ and are used for isolating circuits.
Electrical switchgear is an essential element of any electrical system, protecting operators, bystanders, and equipment from the dangers of current overload. They have applications across a range of public and private infrastructure, including municipal utilities, commercial settings, industrial operations, and disaster response.
Electrical switchgear is required for major civil and private infrastructure such as hospitals, universities, wastewater treatment, substations, and prisons, where high voltage inputs to power a campus or city must have considerable reliability. Ultimately, this ensures the safety of those in the vicinity.
Many commercial applications, such as data centers, require significant electrical load inputs to run their equipment, including coolers, servers, and communication systems. Electrical switchgear protects expensive equipment from damage caused by short circuits, power surges, and outages, which can result in costly downtime and loss of business. Switchgear also ensures a smooth transition to backup energy sources during an outage.
In industrial settings, such as agriculture, manufacturing, or the oil and gas industry, electrical switchgear monitors electrical systems and protects on-site equipment. For large operations that use a lot of power and are located in hard-to-reach areas, including rural farmland, offshore, and jungle drilling, the degradation of an electrical system can put lives at risk. Electrical switchgear can be hardened and weather-proofed to increase safety and equipment longevity in these locations.
Electrical switchgear is critical before and after natural disasters, such as spring storms, hurricanes, blizzards, or flooding. During natural disasters, electrical transmission systems come under extreme pressure from uprooted poles and fallen trees, which can cause major equipment failure at substations and industrial premises. Switchgear provides essential risk control and can also help in the aftermath to depower lines and ensure recovery worker safety.
While there are standard applications for electrical switchgear, it is often customized for specific system needs. At Enercon, we have worked with thousands of clients to create electrical equipment with the exact components, setup, and capacity they need. This includes designing switchgear for various voltage levels, switchgear types, and application requirements.
Depending on need, switchgear is built for low voltage (residential and commercial), medium voltage (industrial) or high voltage (power transmission) applications, and the electrical switchgear must be rated for handling the required loads, or it could put human health and equipment safety at risk. At Enercon, we manufacture our own UL891 low-voltage electrical switchgear in-house and adapt medium-voltage units by integrating our own controls.
Type of switchgear
There are significant variations in types of switchgear, including the insulation method used for disconnecting and isolating circuits. The two main types are: air-insulated (AIS), which is the traditional type of switchgear that creates an air gap between conductors, and gas-insulated (GIS) which uses a gas such as SF6 to insulate between conductors. The latter is commonly deployed when space is tight. There are also switchgear that use fluid and solid-dielectric-in-air as the insulator type.
The end-use of the electrical switchgear will also vary and thus require different components. For example, certain break switches are used for depowering equipment via their circuits, while others will contain fuses and circuit breakers designed specifically to disconnect faulty circuits or prevent sudden current overload.
Custom switchgear can be designed for whatever particular application it is needed for, and most applications are actually unique in their specification. At Enercon, we have extensive experience designing and building custom solutions exactly to our customers’ requirements, including building our own control panels and switchgear, retrofitting existing equipment, or modifying pre-built panels.
Switchgear in action: Michigan State University case study
To deliver a safe and reliable backup energy system for Michigan State University, Enercon custom-designed a control system and switchgear. The resulting medium-voltage switchgear was built around Enercon’s unique touchscreen control system, Evolution, and controlled nine megawatts (12,470 total volts) supplied by four large, diesel-powered 2.25mW engines.
The switchgear was NEMA 1 indoor-rated, paralleling switchgear built for 3-phase and 3-wire, with a 1,200 amp main bus. It consisted of four generator cubicles and a master cubicle, which contained a SCADA monitoring system as well as Enercon’s Evolution touchscreen controls for improved operator control.
For more in-depth case studies, visit our Enercon Insights page.
How to extend the life of switchgear
When considering your electrical switchgear requirements and how they fit into the overall electrical system plans for your facility or campus, there are two options for ensuring ongoing safety and compliance: modernization and replacement.
This involves retrofitting modern electrical switchgear components into your existing control panels and equipment. This option works best if the manufacturer-recommended lifespan of the original components is coming to its end, and you want to replace them with the best available modern components. Updating the components that are currently in your electrical safety equipment without making any significant changes to your electrical system can help you achieve compliance and meet expected safety standards.
Replacing your electrical switchgear involves designing, building, and installing new panels and components. This can be better if you are significantly increasing the voltage inputs and current of the location. Custom-built panels and electrical switchgear allow you to future-proof your electrical system, not only to meet your current needs but also to provide a foundation for future scalability.
Retrofit or replacement: Enercon can help
Whether you choose to upgrade your existing controls with retrofitted electrical switchgear or install new custom-built switchgear, an effective maintenance plan and procedure is essential for keeping components in their best state. Depending on the electrical switchgear's type, purpose, and layout, some factors may be more important, such as regular inspections to ensure seals or coverings are still functioning or cleaning the control panel of debris and dust. Manufacturers' instructions should always be kept close to any electrical switchgear and control panels, ideally in an attached slot on the front of the panel.
At Enercon, we have extensive experience designing, building, retrofitting, and installing electrical switchgear for a wide range of applications across the globe. Whatever your electrical switchgear needs may be, we are confident we can help meet them. Contact us today to learn more about our services and how we can assist with your project.