Many project buyers and site technicians search for MV switchgear and medium voltage switchgear when they buy power equipment, including air insulated solutions, for factories, solar farms and public power projects. A lot of new buyers don't know much about this gear, so they have trouble picking the right one for their work site. This article will show you simple definitions, main jobs, key parts, common product types and practical buying tips for real‑world power projects.
What Is Medium Voltage Switchgear?
Medium voltage switchgear is a full set of cabinet power equipment. It controls power circuits with voltage ranging from 1kV to 52kV, with typical ratings of 3.6kV, 12kV, 24kV and 40.5kV. You can see this equipment in substations, large factories and renewable energy power sites.
You may find different names on project documents. MV switch is often used interchangeably with medium voltage switchgear. It connects the main power supply and end power loads, letting workers easily control power flow for the whole power system.
Core Functions of Medium Voltage Switchgear
This equipment has three key jobs for all power sites.
First, it safely switches power circuits on and off for daily operation.
Second, when overloads or short circuits occur, it quickly cuts off the faulty circuit. This protects cables and other electrical devices from damage.
Third, it creates safe power isolation points. Workers can cut off power easily to do inspections and repairs, with much lower risk of electric shock.
Simply put, we cannot run safe medium-voltage power systems for residential areas, factories and large solar stations without this essential equipment.
Key Components of Medium Voltage Switchgear
Every complete cabinet set is made up of several important working parts that operate together. Circuit breakers serve as the main switching device to open or close power flow. Busbars distribute power from the main supply to different outgoing feeders. Instrument transformers (CT/VT) feed measurement and protection signals, and protective relays trip the breaker when a fault is detected.
Earthing switches drain residual charge so workers can carry out maintenance safely. Current-limiting fuses add extra protection against dangerous over-current events, and dedicated cable compartments keep all wiring neatly contained. All these components fit inside one solid cabinet enclosure to deliver stable, controlled power distribution.
|
Component |
Function |
Key Parameters |
Notes |
|
Circuit Breaker |
Quickly disconnects the circuit under fault conditions |
Rated current 630–4000A; breaking capacity 25–40kA |
Vacuum / SF6 / oil-immersed |
|
Current Transformer (CT) |
Feeds measurement and protection current signals |
Accuracy class 0.2S / 0.5 / 5P20 |
Works with protective relays |
|
Voltage Transformer (VT) |
Measures busbar voltage for metering and protection |
Accuracy class 0.2 / 0.5 / 3P |
Shared by metering and protection |
|
Protective Relay |
Detects faults and sends trip signals to the breaker |
Overcurrent / earth-fault protection |
Microprocessor-based |
|
Isolator (Disconnector) |
Provides safe isolation for maintenance |
No arc-extinguishing capability |
Interlocked with breaker |
|
Earthing Switch |
Reliably earths the circuit before maintenance |
Manual / motor-operated |
Five-prevention interlocking |
|
Surge Arrester |
Diverts overvoltage surges to ground |
Nominal discharge current 5/10kA |
Protects insulation |
|
Busbar |
Collects and distributes current |
Copper / aluminum bars |
Selected by short-circuit withstand |
Main Types of Medium Voltage Switchgear: AIS vs GIS vs Metal-Clad
There are three common types of medium voltage switchgear used in global power projects, and each one fits different site conditions.
AIS (air-insulated) units use regular air for insulation. They cost less to purchase, but they need more installation space. They work best in dry and clean environments.
GIS (gas-insulated) units seal all key live parts inside a metal chamber with insulating gas. They take up far less space and work reliably for coastal, dusty, or underground project sites.
Metal-clad switchgear uses solid metal barriers to separate all internal key parts into independent compartments. It delivers better safety performance, so it is widely used for heavy-duty industrial substations.
Every type has its own advantages and drawbacks. You need to compare them carefully before choosing the right equipment for your project.
How to Choose the Right Medium Voltage Switchgear for Your Project
When you make your selection, start by checking your available installation space, local site environment, total power load, maintenance frequency, and overall project budget. If you have plenty of dry indoor room and want to keep costs down, AIS equipment will meet most ordinary project demands. For tight installation spaces or coastal sites with heavy salt spray, go with GIS-style units. Choose metal-clad models for industrial substations with strict safety requirements and large power loads. Always think about how often your staff will carry out on-site checks and repairs before locking in your final order.
Summary
In short, choose your switchgear according to your actual site conditions, available space and safety needs, instead of only picking the most high-end equipment.
If you're not sure which switchgear fits your power room layout, power load and budget, just send us your project details. LVMA's professional electrical engineers will give you practical selection advice and a complete equipment quote.
About us
Established in 2018, Zhejiang Lvma Electric Co., Ltd. draws on 17 years of electrical engineering expertise. As an ISO 9001:2015-certified enterprise, our key products include intelligent switchgear systems and both oil-immersed and dry-type distribution transformers, exported to Europe, the Middle East, South America, Southeast Asia, and Africa.
Our R&D team holds more than 40 patents, propelling us toward intelligent and sustainable power infrastructure. Through digitalized manufacturing and continuous monitoring, we guarantee stability and safety in every unit.