In the contemporary world of complicated electrical networks, metal enclosed switch gear is one of the important elements ensuring safe and reliable power supply. Wherever electrical energy is generated, transmitted, or consumed, metal enclosed switch gear is applied to guarantee safe electrical distribution. Due to increased energy consumption and complicated grid schemes, metal enclosed switch gear has been widely used in modern medium voltage power systems.
Jiangsu Subian Power Equipment Co., Ltd. creates different types of metal enclosed switch gear plants, from KYN28A-12 withdrawable AC metal enclosed switchgear to HXGN15-12 metal enclosed ring main unit. The product line of Subian Electric comprehensively covers the needs of power supply systems, since it includes equipment for electrical transmission and distribution via substations, for the turbine power plant operation, and for energy delivery to consumers at production facilities. The objective of the given article is to analyze in detail the metal enclosed switch gear and its definitions, types, advantages, industry applications and selection criteria, as well as trends for the future.
What is Metal Enclosed Switch Gear?
Metal enclosed switch gear is a device, which includes metal cabinet, where all components of metal enclosed switch gear assembly are housed. Such components are circuit breakers, disconnectors, fuses, busbars and current transformers. Metal enclosed switch gear is defined by ANSI/IEEE C37.20.2 as an assembly switchgear equipment in metal enclosure. Metal enclosed switch gear helps distribute electricity in a safe manner and help avoid accidents such as internal arc fault and contact or contamination of equipment by external objects.
The difference between metal insulated switch gear and open type switch gear is that the first type of switch gear acts as an impenetrable wall and is able to isolate electrical part from the outer environment, ensuring enhanced protection and reducing clearance and creepage distances. The design of metal enclosed switch gear is compliant to GB/T 11022, GB/T 3906 and IEC 62271 standards and is tested prior to release for compliance with short circuit withstand, internal arc classification and temperature rise criteria.
Main Types of Metal Enclosed Switch Gear
There are three types of metal enclosed switch gear that can be identified based on the working arrangement and withdrawal conditions of the primary switching equipment. Each of the three kinds of equipment can meet the requirements of various operations and make contributions in terms of cost-efficiency, maintenance and safety.
1. Withdrawable (Drawout) Metal Enclosed Switch Gear
KYN28A-12 can be considered representative of withdrawable metal enclosed switch gear. It allows three-phase AC 50Hz operation and is designed for use in systems provided with voltage of up to 12kV. The unit has a removable circuit breaker truck which can be taken out of the enclosure without disconnection of the whole switchboard for repair or replacement. Circuit breakers used with it are mostly of the vacuum type (ZN63A-12 or the similar versions manufactured by ABB and GE).
Withdrawable metal enclosed switch gear makes use of a unique system of interlocks known as ‘five-protection’ interlock the operation of which prevents:
– the circuit breaker truck from insertion or withdrawal in closed position;
– the operation of the circuit breaker in intermediate position;
– the action of earthing switch in case the circuit is energized;
– energization of the circuit once the earthing switch is turned on;
– accessing the cable compartment in case the earthing switch is turned off.This design makes the withdrawable type of metal enclosed switch gear the most convenient solution in critical areas where the risk of downtime is high as a malfunctioning circuit breaker can be immediately replaced with a spare breaker.
Fixed Type Metal Enclosed Switch Gear
HXGN15-12 series is an example of fixed type of metal enclosed switch gear, typically found in ring main units (RMUs). Compact and front accessible, this unit is perfect for usage in urban secondary distribution networks, buildings, and industrial areas. The load-break switch operates based on the spring mechanism. This switch can be combined with current-limiting fuses for overload and short-circuit protection.
Fixed type of metal enclosed switch gear is less expensive than its withdrawable counterparts because it does not use a moving truck and additional devices used for guides and shutters. Yet, the maintenance requires the cubicle to be de-energised. HXGN15-12 series features an efficient interlocking system and it is designed in a manner that allows it to be maintained effectively while making sure that all live parts are shielded to prevent fire or explosion risks.
Armoured Metal Enclosed Switch Gear
KYN61-40.5 belongs to armoured metal enclosed switch gear rated at 40.5kV and fitted for high-voltage installations in substations and heavy industries. It uses additional steel plates separating compartments for breaker and cables. Although the term ‘armoured’ is frequently used in defining metal clad switch gear, KYN61-40.5 refers to metal enclosed switch gear because it does not need grounded metal barriers separating compartments.
Armoured metal enclosed switch gear is famous for its enhanced mechanical strength and reliable arc resistance which makes it good for usage in critical atmospheres. KYN61-40.5 produced by Subian Electric is widely used in power generation plants, big-scale enterprises, and electric substations.
Metal Enclosed Switch Gear vs. Metal‑Clad Switch Gear – Key Differences
Many specifiers often confuse metal enclosed switch gear with metal‑clad switchgear, but they are distinct categories under IEEE and IEC standards. Understanding these differences is crucial when selecting the right equipment for a given project.
| الميزة | Metal Enclosed Switch Gear | Metal‑Clad Switch Gear |
|---|---|---|
| Compartmentalisation | Components (breaker, CT, PT, busbars) are installed in a common compartment without mandatory grounded metal barriers. | Each major component is in its own separate, grounded metal‑enclosed compartment. |
| Main switching device | Usually fixed‑type (though withdrawable versions exist, but not required). | Must be draw‑out (withdrawable) type. |
| Arc‑flash protection | Basic – relies on the overall enclosure and pressure relief. | Enhanced – individual compartment isolation reduces arc energy propagation. |
| Physical size | More compact due to fewer internal partitions. | Larger footprint due to required segregation. |
| التكلفة | Lower – fewer materials and simpler construction. | Higher – extra steelwork and precision engineering. |
| Typical voltage range | 1 kV to 52 kV (IEEE C37.20.9 covers gas‑insulated types). | Usually 5 kV to 38 kV. |
| التطبيق | Secondary distribution, industrial plants, commercial buildings. | Primary distribution, critical infrastructure, high‑reliability utilities. |
In short, metal enclosed switch gear offers an excellent balance between performance and economy for the majority of medium‑voltage applications, while metal‑clad switchgear is reserved for projects where the highest level of safety and continuity is mandated.
Essential Benefits of Metal Enclosed Switch Gear
Through years of use, metal enclosed switch gear has proved itself in numerous applications. The following benefits create a strong justification for its extensive use by engineers and facility managers all over the world.
1. The Highest Degree of Safety
Metal sheets ensure the complete enclosure of live conductors, thus preventing accidental contact. In addition, the enclosure is capable of standing against internal arc faults for a certain period of time (usually 0.5-1 seconds) and directs the hot gases through the pressure relief flaps located on the top of the device.
2. Minimal Space Requirements
The design of metal enclosed switch gear is characterized by such features that are absent in metal clad switch gear, which makes it possible to save space (in terms of floor area). This factor is especially important in cities where the values of real estate are very high.
3. Adaptability to Different Customer Needs
Subian Electric provides metal enclosed switch gear for voltages from 12 kV to 40.5 kV and currents from 630 to 5000 A. Switching devices may use vacuum or SF6 circuit breakers, fuse disconnectors, and many auxiliary devices – such as current transformers, voltage transformers, surge arresters, etc.
4. Highly Reliable Protection
Modern metal enclosed switch gear is supplied with intelligent electronic devices capable of providing overcurrent and earth fault protections. With optional modules, remote controlling is possible through SCADA systems.
5. Compliance with Global Standards
All devices manufactured by Subian Electric in this category are compliant with GB 3906, IEC 62271-200 and ANSI/IEEE standards and go through extensive type tests in order to ensure that they are in line with the requirements of foreign countries when it comes to electric safety and performance.
Common Uses of Metal Enclosed Switch Gear
Due to the flexibility of metal enclosed switch gear, it is used in a variety of different industries:
Power Generation Stations – for auxiliary power distribution and connection to generators.
Utility Substations – for primary voltage transformation, secondary voltage transformation, and protection of feeds.
Industrial Applications – for providing power to large motors, furnaces, and factories.
Commercial Buildings and High – Rise Developments – for incoming power and supplying electricity to different floors and devices.
Wind and Solar Farms – for power collection and transfer of renewable power to the grid.
Railways and other modes of transport – for connecting traction power and providing supply for stations.
Data Centres – for making sure that power supply is continuous and unending.
In each of these settings, metal enclosed switch gear provides the essential functions of switching, protection, and isolation, contributing to the overall resilience of the electrical infrastructure.
The Right Way to Select Metal Enclosed Switchgear
Choosing the right metal enclosed switchgear for the task means going through a systematic assessment of a number of electrical and financial factors. Look at the following points to assist in your decision.
1. Find out the system voltage and level of insulation
The rated voltage of the switchgear has to be equal to the nominal system voltage, like 12 kV, 24 kV, or 40.5 kV. You also need to take into account the basic lightning impulse withstand voltage (BIL) and power frequency withstand voltage, depending on the altitude and pollution level at the place of installation.
2. Determine continuous and short-circuit currents
You have to calculate the maximum continuous current so that you can choose the necessary rating for the busbar and the circuit breaker. You have to be aware of the expected short-circuit currents, which can be around 25 kA, 31.5 kA, 40 kA, or 50 kA.
3. Decide to go with the withdrawable or fixed design
Make sure that you select a withdrawable design in case you have to minimize downtimes and there are spare circuit breakers available. Choose fixed units for cost-sensitive projects when outages can be planned in advance.
4. Assess environmental factors
IP4X is most probably a standard protection rating needed for indoor installations. Outside installations need weatherproof housings (not less than IP54 rating), and, in some cases, heating for condensation prevention. Also, in high-altitude or polluted areas where derating and additional insulating are necessary, the installation becomes more complicated.
5. Specify protection and control scheme
Select the necessary protection features (overcurrent, ground fault, etc.) and communication protocols (like Modbus or IEC 61850). Choose the needed protection relays and transformers.
6. Think about future expansion
It is very important that the switchgear line can allow for adding more feeders or busbars in the future. Subian Electric has metal enclosed switchgear designed in the form of modular panels that are easy to extend.
Subian Electric is also happy to provide technical consultations for free. Just let them know about the voltage, current, application, and location of the installation, and their engineers will help to choose the right switchgear.
Maintenance and Lifecycle Considerations
Proper maintenance is essential to ensure the long‑term reliability of metal enclosed switch gear. Routine inspections should include:
- Visual checks for corrosion, loose connections, and signs of overheating.
- Cleaning of insulators and busbars to prevent tracking.
- Functional testing of interlocks, earthing switches, and auxiliary contacts.
- Lubrication of moving parts as per manufacturer’s recommendations.
- Measurement of contact resistance and insulation resistance (megger test).
- Periodic timing tests for circuit breakers and operating mechanisms.
With proper care, a quality metal enclosed switch gear can have a service life of 25 to 30 years. Subian Electric supplies detailed operation and maintenance manuals with each shipment, and also offers after‑sales support including spare parts and on‑site troubleshooting.
Future Trends in Metal Enclosed Switch Gear
The landscape of metal enclosed switch gear is evolving rapidly, driven by digitalisation and the push for greener energy systems. Emerging trends include:
- Gas-insulated alternatives – SF6 or environmentally friendly gas-insulated MESG with smaller dimensions.
Monitoring with the internet of things (IoT) – sensors for detecting partial discharge, temperature, and humidity that send information to analytical devices based in the cloud for predictive maintenance.
Technology of solid insulation – use of solid insulation materials instead of gas or air in order to avoid environmental issues.
Compact modular design – which speeds up setup and makes future upgrades easier.
Arrangement for using in renewable energy systems – modern switchgear manufactured with the ability of receiving power from solar and wind plants and reacting to fault levels.
Subian Electric is at the forefront of these innovations, continuously refining its metal enclosed switch gear portfolio to meet the demands of smart grids and sustainable energy infrastructure.
الخاتمة
Metal enclosed switch gear remains the most widely adopted technology for medium‑voltage power distribution, thanks to its proven safety, compactness, and cost‑effectiveness. Whether you are designing a new substation, upgrading an industrial plant, or expanding a commercial complex, selecting the right metal enclosed switch gear is a critical decision that impacts system reliability, operator safety, and total cost of ownership.
With decades of manufacturing experience and a commitment to international quality standards, Subian Electric offers a full spectrum of metal enclosed switch gear solutions tailored to your specific needs. From the versatile KYN28A‑12 withdrawable type to the robust KYN61‑40.5 armoured design, each product is engineered to deliver outstanding performance in the most demanding environments.
For detailed specifications, customised proposals, or technical advice, please visit the official Subian Electric website or contact our expert team. We are dedicated to helping you achieve a safe, efficient, and future‑ready electrical distribution system with our state‑of‑the‑art metal enclosed switch gear.
— This article was prepared by the technical marketing team at Jiangsu Subian Power Equipment Co., Ltd., based on extensive field experience and international standards.