Views: 0 Author: Luna Publish Time: 2026-08-04 Origin: Zhejiang Shengxian Electric Technology Co., Ltd
In medium voltage distribution, Metal-Clad Withdrawable Switchgear is a name that comes up again and again. You will find it in power plants, substations, factory electrical rooms, and commercial building distribution centers.
It is one of the most widely used medium voltage switchgear solutions worldwide, fully compliant with IEC 62271-200.
But many customers are not entirely familiar with it: What exactly is it? Why is it so popular? How is it different from other types of switchgear?
This article covers the construction, features, applications, and selection considerations of this MV switchgear – so you can understand why it is the preferred choice for so many projects.
Metal-Clad Withdrawable Switchgear is a type of indoor medium voltage metal-enclosed switchgear used in 3.6–12kV, 50Hz power systems for receiving, distributing, controlling, and protecting electrical energy.
Key features at a glance:
Metal-clad: Fully enclosed in a metal enclosure with grounded metal partitions between compartments
Withdrawable: The circuit breaker is mounted on a removable trolley that can be rolled out for maintenance
Indoor use: Designed for indoor installation
Compliant with IEC 62271-200: Meets international standards for AC metal-enclosed switchgear and controlgear
The enclosure is manufactured from zinc-coated steel sheets using high-precision CNC processing, offering excellent corrosion resistance and mechanical strength. The interior is divided by metal partitions into four independent compartments:
Compartment | Location | Key Components |
|---|---|---|
Circuit Breaker Compartment | Middle-front | Vacuum circuit breaker on withdrawable trolley |
Busbar Compartment | Rear-upper | Main busbars, branch busbars |
Cable Compartment | Rear-lower | Cable terminations, current transformers |
Instrument Compartment | Front-upper | Protection relays, meters, control panel |
The breaker trolley is positioned at a convenient working height in the middle of the cabinet, making operation and maintenance easy.
Each compartment has its own independent pressure relief channel. In the event of an internal fault, hot gases are directed safely upward and outward, protecting the operator.
① Withdrawable Design – Easy Maintenance
The circuit breaker is mounted on a removable trolley. For inspection or replacement, simply roll the trolley out – no need to de-energize the entire switchgear assembly. The trolley has three distinct positions: Service Position, Test/Isolation Position, and Withdrawn Position – each with clear indication and secure positioning.
② Comprehensive Interlocking System
The switchgear is equipped with both mechanical and electrical interlocks to ensure safe operation:
Prevents closing/opening the isolation device under load
Prevents opening/closing the circuit breaker mistakenly
Prevents closing the breaker when the earthing switch is closed
Prevents closing the earthing switch when the circuit is live
Prevents opening the compartment door when the circuit is live
③ Flexible Configuration
The design accommodates vacuum circuit breakers from various manufacturers, both international brands and high-quality local alternatives – offering flexibility to meet different project specifications and budget requirements.
④ Good Protection Rating
The enclosure provides IP4X protection, with IP2X protection when the breaker compartment door is open – effectively preventing solid foreign objects from entering.
Parameter | Value Range |
|---|---|
Rated voltage | 3.6kV / 7.2kV / 12kV |
Rated frequency | 50Hz |
Rated current | 630A – 4000A |
Rated short-circuit breaking current | 20kA – 50kA |
Rated short-time withstand current (4s) | 20kA – 40kA |
Rated peak withstand current | 50kA – 100kA |
1min power frequency withstand voltage | 42kV |
Lightning impulse withstand voltage | 75kV |
Protection rating | IP4X (enclosure) / IP2X (door open) |
Application | Description |
|---|---|
Power plants | Medium/small generator connections |
Substations | Power receiving and distribution |
Industrial plants | Factory and mining distribution systems |
Infrastructure | Large buildings, transportation facilities |
Motor control | Starting and protecting large MV motors |
When specifying this switchgear, the following parameters should be defined:
Item | Notes |
|---|---|
Rated voltage | 3.6kV / 7.2kV / 12kV |
Rated current | Select based on load (630–4000A) |
Short-circuit breaking capacity | Must exceed the system‘s prospective short-circuit current |
Breaker brand | Options available across different price and performance levels |
Trolley types | Breaker trolley, PT trolley, metering trolley, isolation trolley |
Cable entry/exit | Cable incoming/outgoing or overhead line options |
Metal-Clad Withdrawable Switchgear has become one of the most popular MV switchgear solutions worldwide because it strikes an excellent balance between safety, reliability, flexibility, and cost-effectiveness.
If you are planning a medium voltage distribution project, this is a solution worth serious consideration.
For project-specific selection advice, feel free to contact us.
Contact us
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WhatsApp: +195 1818 9858
Mail: lunahe927@gmail.com
