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.
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.
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-energised 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.
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Primary insulator: pure air with vacuum interruption
Best for: Large substations where space isn't limited, but cost is a priority.
Environmental trend: Growing - simple, reliable, and completely eliminates the need for insulating gases.
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 optimised predictive maintenance. Combined with our EcoCare service, which offers 24/7 remote monitoring, expert support, and AI‑driven insights, these solutions maximise uptime, reduce costs, and extend asset life.
FAQs
Medium voltage typically ranges from 1 kV to 36 kV (IEC) or up to 69/72 kV (ANSI/NEMA), depending on regional standards.
SF₆ is a gas with a very strong impact on global warming. Because of this, new regulations are beginning to restrict its use in new equipment. The industry is now shifting to alternative options such as pure air, vacuum, or solid insulation materials, which deliver the same performance without harming the environment.
Arc flash, insulation failure, mechanical wear, and improper operation can occur. Proper personal protective equipment, such as protective clothing, helmets, and goggles, along with established procedures, is essential.
Yes. Many modern MV switchgear systems can be monitored and operated remotely using digital tools. This helps detect issues early, plan maintenance, and keep power systems operating smoothly.
Typically, 20 to 30 years, depending on usage, environmental conditions, and maintenance practices.
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