Switchgear: Medium voltage explained
Ever wonder what keeps the power flowing? Discover the role of medium voltage switchgear in managing electricity across the grid. Scroll down for insights and tailored solutions or visit our product page for more details.
Switchgear is a broad term for the central control equipment in an electrical power system. If you are looking for a clear switchgear definition, it is the equipment that connects, manages, and protects the entire circuit by controlling its current flow. For many, the question "what is switchgear?" is best answered by understanding its role as the "traffic controller and security guard" of the power grid. Specifically, medium voltage switchgear (MV switchgear) is the essential electrical switchgear equipment used to control, protect, and isolate electrical circuits operating at medium voltage typically ranging from 1 kV to 72 kV. It is a critical component in the electrical distribution system, ensuring power is managed efficiently and reliably from transmission lines to the end consumer.
The power grid operates using three main voltage classes:
- Low voltage (LV): up to 1 kV. It powers standard appliances in homes and offices. LV switchgear manages and protects circuits in commercial and industrial facilities, ensuring reliable distribution and guarding against faults like short circuits, overloads, and earth faults.
- Medium voltage (MV): 1 kV to 36 kV, or up to 72 kV depending on regional standards — used to distribute power across cities, industrial parks, and renewable sites. MV electrical switchgear bridges high-voltage transmission and low-voltage use, ensuring grid stability with advanced fault detection and isolation for overloads, short circuits, arc flash, and thermal hotspots risks.
- High voltage (HV): above 69 kV, depending on regional standards — used for long-distance transmission across regions or countries.
MV switchgear performs three core functions essential to grid reliability: It detects faults, interrupts hazardous currents within milliseconds, enables load switching, and enhances worker protection during maintenance.
Protection
It serves a critical function as the switchgear’s primary mechanism for protecting the system against catastrophic failures.
Fault detection
Internal sensors and protective relays constantly monitor current and voltage for sudden surges caused by short circuits or overloads.
Rapid interruption
Upon detection, the relay commands a circuit breaker to open the circuit in milliseconds, isolating the damaged section before the massive energy can cause fire or equipment destruction.
Control
It serves a key management role, enabling human operators and automated systems to manage the flow of electricity.
Load switching
Engineers can close or open specific circuits to connect or disconnect equipment, allowing power to be rerouted during equipment upgrades or maintenance.
Monitoring and automation
Modern MV switchgear is often digitally native, allowing for remote monitoring and control, which improves efficiency and grid resilience (smart grid functionality).
Isolation
It acts as a critical assurance, helping protect workers during maintenance on critical systems and reducing operational risks.
Visible separation
Using a disconnect switch, also known as an isolator, an air gap is created to separate equipment from live power, ensuring the circuit is fully de‑energized for work.
Switching devices
The separation can also be achieved through devices such as a fuse switch disconnector, an earthing switch, or a circuit breaker.
If you examine any electrical switchgear cabinet, you will find these essential devices that support control and system reliability.
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Circuit breaker
Breaks the current flow when a fault occurs and is essential for arc quenching and system protection.
Medium voltage (MV) switchgear relies on air, gas, or solid insulation to keep electrical parts electrically separated. This choice affects equipment size, maintenance requirements, and environmental footprint. Today, manufacturers are moving away from older SF₆‑based gas designs and adopting alternative technologies with lower environmental impact. SF₆ has an extremely high global warming potential.
Air-insulated switchgear (AIS) uses air to insulate live electrical parts. It is used for both primary and secondary medium-voltage distribution. Primary AIS is typically used closer to substations and transformers, while secondary AIS distributes power to local loads.
Best for: Applications where space is available and simplicity and reliability are priorities.
Environmental trend: AIS uses pure air instead of insulating gas such as SF₆.
Medium voltage (MV) switchgear is governed by international standards such as IEC 62271-200 and ANSI/IEEE C37 series, which define design, testing, and operational requirements for metal-enclosed switchgear typically operating from 1 kV up to 52 kV (IEC) or up to 69 kV (ANSI). These standards ensure reliability and environmental compliance across global power systems. Regular maintenance is essential to ensure long-term performance and reliability. Typical tasks include:
- Visual inspections: checking for physical wear, corrosion, or damage
- Thermal imaging: detecting hotspots that may indicate loose connections or abnormal resistance
- Functional testing: verifying that protection devices (e.g., relays, breakers) operate correctly
Modern MV switchgear leverages IoT sensors and advanced data analytics to identify abnormal conditions. By monitoring key parameters such as temperature, humidity, partial discharge and circuit breaker health, it enables optimized predictive maintenance. Combined with our EcoCare service, which offers 24/7 remote monitoring, expert support, and AI‑driven insights, these solutions maximize uptime, reduce costs, and extend asset life.
MV switchgear supports the following monitoring functions:
- Internal arc detection: Optical light sensors allow relays to clear internal arc conditions faster, decreasing risks for operators and potential equipment damage.
- Environmental monitoring: Wireless sensors monitor installation conditions, detecting ambient temperature and humidity that may accelerate aging.
- Thermal monitoring: Wireless sensors help detect temperature anomalies, prompting diagnosis of potential faults, fire risks, and maximizing uptime.
- Partial discharge monitoring: Optional expert-driven service to continuously monitor and detect abnormal activity linked to insulation degradation.
- Switchgear HMI: Optional local display of the latest status, health conditions, and alarms
- Comprehensive breaker health: Enhanced monitoring of the entire circuit breaker, wear, speed, and component health status.
- Local or Remote control: Digital operation of CB Open/Close and racking from outside of the arc flash zone.
Explore our latest MV Panorama catalog featuring a comprehensive range of efficient and sustainable medium voltage products and components. Access detailed specifications and product information today.
Explore our future‑ready solutions that support reliable operation and keep sustainable power flowing seamlessly.
FAQs
SF₆-free medium voltage switchgear helps reduce environmental impact by eliminating the need for SF₆ gas and avoiding the challenges associated with gas recovery, recycling, and end-of-life treatment. Schneider Electric's SF₆-free solutions use pure air and vacuum technology while maintaining benefits such as a compact footprint, three-position switching, transformer protection capabilities, and digital connectivity. Pure air switchgear can also help reduce the switchgear's carbon footprint across its lifecycle.
AirSeT uses pure air for insulation and vacuum technology for current interruption, eliminating the need for SF₆ gas. The solution combines these technologies in a patented architecture called Shunt Vacuum Interruption (SVI™), enabling a sustainable medium voltage switchgear design while maintaining reliability, operational safety, and compact dimensions.
Shunt Vacuum Interruption (SVI™) is Schneider Electric's patented switching technology used in AirSeT™ medium-voltage switchgear. SVI™ combines pure air insulation with vacuum interruption technology in a single architecture, removing the need for SF₆ gas while helping customers maintain performance, safety, and reliability.
Modern digital medium voltage switchgear can include internal arc detection, switchgear HMI visualization, thermal monitoring, circuit breaker health monitoring, partial discharge monitoring, environmental monitoring, and local or remote control functions. Connected sensors continuously monitor asset condition and support informed maintenance decisions.
Partial discharge monitoring helps identify abnormal electrical activity associated with insulation degradation before it develops into a serious fault. Schneider Electric's PowerLogic™ PD100 provides direct partial discharge measurement using an IEC 60270-based approach and advanced algorithms that remove background noise and assess risk trends. One PD100 can monitor up to three switchgear units.
Predictive maintenance uses connected sensors, continuous monitoring, analytics, and expert recommendations to identify potential issues before failures occur. Through EcoCare membership, organizations gain remote monitoring, alarm management, advanced analytics, and expert support that can help reduce electrical failure risk and unplanned downtime by up to 75%, while reducing on-site maintenance activities by up to 40%.
Schneider Electric's application guide recommends solutions by use case. For data centers: GM AirSeT™, PIX™, F400, PremSeT™, SM AirSeT™, DVCAS, and RM AirSeT™. For renewable energy and power-grid applications: GM AirSeT™, WS-G, GHA, DVCAS, and RM AirSeT™. For water and wastewater facilities: GM AirSeT™, MCSeT™, PIX™, GMA, RM AirSeT™, RM6™, and SM AirSeT™.
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