In medium- and high-voltage power distribution systems, selecting the appropriate switchgear architecture is a critical engineering decision that directly affects operational reliability, equipment lifespan, and personnel safety. Among the various switchgear designs available, metal-clad switchgear has become the preferred solution for utility substations, industrial facilities, commercial buildings, and infrastructure projects because of its superior safety, maintainability, and performance.
As an ISO9001-certified manufacturer of power distribution equipment, Zhejiang Gangheng Electric Co., Ltd. (GangHeng) provides metal-clad switchgear designed to meet international standards while delivering long-term reliability in demanding operating environments.
What Is Metal-Clad Switchgear?
According to IEC 62271-200 and GB3906, metal-clad switchgear is a metal-enclosed switchgear assembly in which every major functional compartment-including the circuit breaker compartment, main busbar compartment, cable compartment, and low-voltage control compartment-is completely separated by grounded metal partitions.
Unlike conventional metal-enclosed switchgear, true metal-clad switchgear uses withdrawable (draw-out) circuit breakers together with automatic protective shutters. When the circuit breaker is withdrawn for maintenance, the shutters automatically cover the energized stationary contacts, preventing accidental contact with live components and significantly improving operator safety.
This compartmentalized structure also helps contain internal faults, reducing the risk of damage spreading throughout the switchgear assembly.
Core Engineering Advantages of Metal-Clad Switchgear
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Superior Operational Safety with Comprehensive Interlocking
Safety is one of the primary reasons why metal-clad switchgear is widely adopted in voltage classes ranging from 12 kV to 40.5 kV.
The complete metal compartmentalization isolates each functional section, so if an internal fault or arc occurs in one compartment-such as the cable chamber-the grounded metal barriers help contain the fault and prevent it from propagating to adjacent compartments.
Modern metal-clad switchgear also incorporates a comprehensive "Five-Proof" mechanical interlocking system that prevents dangerous operating errors. These interlocks help prevent actions such as withdrawing a circuit breaker while it is carrying load, closing a grounding switch on an energized circuit, or accessing live compartments during operation.
In addition, pressure-relief ducts located at the top of each compartment safely direct hot gases and arc energy away from personnel if an internal arc fault occurs, further enhancing workplace safety.
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Excellent Durability and Corrosion Resistance
Industrial facilities often expose electrical equipment to dust, vibration, humidity, and corrosive environments. Metal-clad switchgear is specifically designed to withstand these demanding conditions.
GangHeng's KYN28A-12 and KYN61-40.5 series are manufactured using high-quality aluminum-zinc (Al-Zn) coated steel sheets processed with precision CNC punching, bending, and forming technology. This construction provides excellent structural rigidity while offering long-term corrosion resistance that supports decades of reliable operation.
The enclosure also provides IP4X protection, preventing dust, debris, and small foreign objects from entering the switchgear and protecting internal insulation components from contamination.
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Reduced Downtime Through Withdrawable Circuit Breakers
For facilities such as power plants, steel mills, petrochemical complexes, and data centers, minimizing maintenance downtime is essential.
Metal-clad switchgear utilizes withdrawable vacuum circuit breakers-including models such as the ZN85-40.5, VS1, and VD4-mounted on movable trucks. This design allows operators to remove the breaker for inspection, testing, or replacement without shutting down the complete busbar system, significantly reducing maintenance time and improving system availability.
When the breaker is withdrawn, automatic metal shutters immediately cover the energized stationary contacts, providing an additional level of protection for maintenance personnel.
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Flexible Configuration and System Integration
Metal-clad switchgear is highly adaptable to different power system configurations and project requirements.
It supports a wide range of busbar arrangements, including single-bus systems, sectionalized busbars, overhead incoming and outgoing feeders, and bottom cable entry configurations.
The modular design also allows easy integration of current transformers (CTs), voltage transformers (PTs), surge arresters, intelligent protection relays, and modern automation equipment such as FTUs and RTUs for smart substations and digital power distribution systems.
Metal-Clad vs. Fixed Metal-Enclosed Switchgear
Although both metal-clad and metal-enclosed switchgear provide enclosed electrical protection, their structural designs and maintenance capabilities differ significantly.
Metal-clad switchgear uses withdrawable circuit breakers, complete metal separation between all functional compartments, and automatic protective shutters. These features greatly reduce maintenance risks while allowing servicing without extensive system shutdowns. As a result, metal-clad switchgear is widely used in 12 kV, 35 kV, and 40.5 kV high-power distribution systems where operational continuity is essential.
Fixed metal-enclosed switchgear, such as the XGN17 and XGN15 series, permanently installs switching devices inside the enclosure. These systems generally offer a more compact footprint and lower initial investment, making them suitable for secondary distribution networks and ring main unit (RMU) applications. However, maintenance typically requires equipment isolation and de-energization, resulting in longer service interruptions compared with withdrawable metal-clad designs.
Typical Applications of Metal-Clad Switchgear
Because of its high interrupting capacity, robust construction, and excellent operational safety, metal-clad switchgear is widely used across numerous industries.
Power generation facilities, including hydroelectric plants, thermal power stations, and utility substations, rely on metal-clad switchgear for reliable transmission and distribution.
Heavy industrial sectors such as mining, metallurgy, petrochemical processing, and steel manufacturing depend on these systems to support continuous 24-hour production while minimizing maintenance-related downtime.
Metal-clad switchgear is also commonly installed in commercial buildings, transportation infrastructure, railway systems, airports, and international utility projects where dependable medium-voltage power distribution is essential.
One example is a utility project in Tanzania, where GangHeng supplied customized KYN61-40.5 withdrawable metal-clad switchgear. The equipment was unpacked, installed, tested, and successfully energized within just five days despite challenging tropical site conditions.
Frequently Asked Questions
1. What is the difference between metal-clad and metal-enclosed switchgear?
All metal-clad switchgear belongs to the broader category of metal-enclosed switchgear, but not all metal-enclosed switchgear qualifies as metal-clad.
Metal-clad switchgear requires complete metallic separation between every functional compartment, withdrawable primary switching devices, and automatic protective shutters covering energized stationary contacts. These features provide higher safety, improved maintainability, and better fault containment compared with conventional metal-enclosed designs.
2. What voltage levels does GangHeng's metal-clad switchgear support?
GangHeng manufactures metal-clad switchgear for a wide range of voltage levels, including 10 kV and 12 kV systems with the KYN28A-12 series, as well as 35 kV and 40.5 kV systems using the KYN61-40.5 series.
The company also supplies 0.4 kV low-voltage switchgear, including GCS and MNS systems, providing complete power distribution solutions for industrial plants and substations.
3. What are the typical lead times for international EPC projects?
Production schedules depend on project size and customization requirements.
Standard switchgear orders valued at approximately USD 300,000 are typically completed within 30 days, while larger substation projects ranging from USD 700,000 to USD 1.5 million generally require 45 to 60 days. All equipment is manufactured under strict ISO9001 quality management procedures and supported by comprehensive type-test documentation.
Partner with GangHeng Electric
Since 2004, Zhejiang Gangheng Electric Co., Ltd. has established itself as a trusted National High-Tech Enterprise specializing in medium- and high-voltage switchgear, power transformers, prefabricated substations, and intelligent power distribution solutions.
By combining international manufacturing standards, advanced engineering capabilities, and flexible customization, GangHeng delivers reliable metal-clad switchgear for utilities, EPC contractors, and industrial customers around the world.
If you are looking for internationally certified, custom-engineered metal-clad switchgear with competitive pricing and dependable global delivery, contact GangHeng Electric's engineering team for technical consultation and a customized quotation.
Email: zjgh2@ghswitchcabinet.com
Website: https://www.ghswitchcabinet.com
References
- Electrical Equipment Handbook: Design and Application
- Power System Protection and Switchgear Manual