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Medium Voltage Switchgear: Definition, Type, and Component

  • Writer: Derrel Gerary
    Derrel Gerary
  • 1 day ago
  • 4 min read
what Medium Voltage Switchgear is

Medium voltage switchgear is an essential part of modern electrical infrastructure. It ensures the safe distribution, control, and protection of electricity in voltage ranges typically from 1 kV up to 36–69 kV. In this comprehensive guide, we explore what medium voltage (MV) switchgear is, its components, operating principles, and the different types available—while also highlighting how Leistung offers cutting‑edge MV switchgear solutions for industrial, utility, and renewable energy applications.


Medium Voltage Switchgear Is…


Medium voltage switchgear refers to assemblies of electrical equipment, such as circuit breakers, disconnectors, fuses, relays, busbars, and surge arresters, packaged within an enclosure designed to manage and protect electrical power systems in the mid‑voltage range (1–36 kV, up to around 69 kV).


Definition & Purpose


MV switchgear is used to:


  • Control the flow of electrical power by switching circuits on/off.

  • Protect against overloads, short circuits, and faults by disconnecting faulty parts.

  • Isolate parts for safe maintenance.

  • Monitor system health via relays and digital instrumentation.


Why "Medium" Voltage?


Electrical infrastructure is categorized by voltage levels:


  • Low voltage (LV): < 1 kV

  • Medium voltage (MV): 1 kV to 36–69 kV

  • High voltage (HV): 75 kV up to 230 kV+


This level is common in distribution networks, especially in industrial, municipal, and renewable energy systems, and is critical for bridging transmission and low‑voltage supply networks.


MV Switchgear in Daily Use


You'll find MV switchgear:


  • In distribution substations connecting to the grid .

  • Behind industrial plants, data centers, renewable power facilities (solar, wind, hydro).

  • Incorporated into ring main units (RMUs) serving urban/utility distribution.


Leistung specializes in MV switchgear for substations, industrial distribution systems, and bespoke RMU setups, offering solutions that enhance reliability, safety, and scalability.


Medium voltage switchgear is a composite system comprised of multiple essential components, each playing a specific role in safety and functionality:


Circuit Breakers


  1. The heart of MV switchgear—designed to interrupt fault currents in milliseconds.

  2. Common types include vacuum, SF₆ gas, oil, or air‑blast breakers.

  3. MV circuit breakers are usually vacuum or SF₆‑based and meet IEC/IEEE standards.


Disconnectors (Isolators)


  1. Manually or motor-operated, these ensure sections are de‑energized for maintenance.

  2. Not load‑breaking—they simply isolate parts after breakers have opened.


Fuses & Surge Arresters


  1. Fuses provide primary overcurrent protection—fast and reliable .

  2. Surge arresters (e.g., lightning arresters) protect against transient voltage surges.


Relays & Control/Protection Systems


  1. Electromechanical, electronic, or digital protection relays detect faults and command circuit breakers.

  2. Modern systems include remote monitoring, communication protocols like IEC 61850, and control automation.


Busbars & Insulating Systems


  1. Copper/aluminum conductors distribute current within the enclosure.

  2. Insulation via air, SF₆ gas, vacuum, oil, or solid mediums prevents flashovers.


Enclosures


  1. Metal‑enclosed: Compartments of live parts, breakers, buses—standard in indoor installations.

  2. Metal‑clad: Individual components are compartmentalized with grounded barriers.

  3. Pad‑mounted and vault types are designed for outdoor installations.



Each component is part of a cohesive whole, a well-designed MV switchgear performs multiple functions seamlessly. Leistung’s MV switchgear systems are built to meet diverse configurations, offering SF₆‑free options, smart integration, and support for future expansion.


How Does Medium Voltage Switchgear Work?


Understanding MV switchgear operation requires a look at its dynamic process:


Step 1 – Power Flow & Distribution


Incoming power (e.g., 20 kV from a substation) enters via a feeder. Busbars distribute this power to multiple outgoing feeders.


Step 2 – Fault Detection


  • Protection relays continuously monitor current, voltage, frequency.

  • If fault conditions are detected (overcurrent, earth fault, arc flash), the relay issues a trip command.


Step 3 – Circuit Interruption


  • The circuit breaker responds within milliseconds to isolate the faulty section using vacuum, SF₆, or air arc interruption.


Step 4 – Isolation for Maintenance


  • Once the faulted section is offline, a disconnector is opened manually or remotely.

  • This guarantees a safe environment for maintenance personnel.


Step 5 – Re‑energization and Normal Operation


After repairs, the disconnector is closed, and the circuit breaker can be reset and re‑energized. Automatic reclose (ARC) mechanisms can be employed for transient faults.


Monitoring & Smart Control


Modern MV switchgear systems integrate digital monitoring, asset management, predictive maintenance, and remote operations. Leistung’s systems include options for IoT connectivity, SCADA compatibility, and future upgrades, helping customers reduce downtime and increase efficiency.


Types of Medium Voltage Switchgear

MV switchgear comes in varied configurations, based on insulation medium, construction, environment, and application.


Based on Insulation Medium


Uses ambient air for insulation—cost‑effective and easy to maintain, but large.

Compact, uses SF₆ gas to insulate live parts, ideal for confined spaces but costs more and requires gas handling.

  1. Hybrid Switchgear

Combines AIS and GIS benefits—compact like GIS, economical like AIS.

  1. Oil‑ or Vacuum‑Insulated

Oil for arc interruption and insulation; vacuum for compact and low‑maintenance breakers.


Based on Construction & Application


Entire switchgear is enclosed in a grounded metal cabinet.

  1. Metal‑Clad

Each functional unit is compartmentalized; grounded barriers provide safety.

  1. Arc‑Resistant

Secondary containment protects personnel by directing arc‑blast energy safely.

  1. Pad‑Mounted

Outdoor, weather‑sealed units often used in utilities or residential feeders.

  1. Vault/Subsurface

Installed underground or in vaults; uses SF₆ or solid‑dielectric systems.

  1. Ring Main Units (RMUs)

Compact, sealed looped units providing redundancy and fault isolation.

  1. Custom or Mobile Units

Tailor‑made for special needs: arc flash, mobile substations, mining, heavy industry, etc.


Based on Use in Distribution System


  1. Primary Distribution Units

Manage supply from HV to MV. Typically found in substations.

  1. Secondary Distribution Units

Step down and distribute power from MV to LV to consumer end-points.


Advantages & Applications of Medium Voltage Switchgear


  1. Reliability and Continuity

Enables selective isolation of faults, minimizing outages.

  1. Enhanced Safety

Protects equipment, personnel, and infrastructure with fast fault clearing and arc‑resistant design.

  1. Space Efficiency

GIS and pad‑mounted units save space compared to AIS.

  1. Maintenance & Lifecycle Cost

Vacuum and SF₆ solutions reduce maintenance intervals; metal‑clad construction simplifies servicing.

  1. Future‑Ready and Smart Integration

Integration with remote SCADA, IEC 61850, predictive analytics—Leistung supports smart grid capabilities.

  1. Environmental Considerations

SF₆‑free GIS alternatives and hybrid systems reduce greenhouse gas impact—Leistung offers sustainable switchgear choices.


Why Choose Leistung Medium Voltage Switchgear


  • Quality & Compliance: Manufactured to meet IEC, IEEE, and national safety standards.

  • Custom Design: Tailored to voltage ratings, configuration, footprint, and environmental needs.

  • SF₆‑free Options: Advanced hybrid and eco-friendly systems catering to sustainability.

  • Smart Features: Remote control, condition monitoring, digital protections included.

  • Comprehensive Support: From project design to commissioning, training, and lifecycle services.


Medium voltage switchgear is the backbone of safe and efficient power distribution in today’s electrified world. From protecting industrial operations to enabling smart grid functions, its role cannot be overstated. By offering Leistung’s MV switchgear, your facility gains:


  • Enhanced safety and reliability

  • Scalable and future‑proof infrastructure

  • Space‑saving designs

  • Maintenance‑friendly systems

  • Eco‑conscious solutions

 
 
 

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