Differences and Applications of Four Types of Low-Voltage Switchgear: GGD, GCK, GCS and MNS

Low-voltage switchgear is a piece of equipment used for power distribution and control in power systems, playing a vital role in power systems. Such switchgear is generally applied in low-voltage power distribution systems to distribute electric energy to various electrical equipment or loads. A low-voltage switchgear usually consists of multiple compartments, each containing various electrical components such as circuit breakers, fuses, contactors, transformers, etc. These components are connected by busbars to form a complete power distribution and control system. This article explains the differences and applications of four types of low-voltage switchgear: GGD, GCK, GCS and MNS.

What Is Switchgear?

Switchgear is a complete set of power distribution devices assembled with primary and secondary equipment in accordance with specified circuit schemes, used to control and protect lines and equipment. The structure of switchgear is generally similar, mainly divided into busbar chamber, circuit breaker chamber, secondary control chamber (instrument chamber) and feeder chamber, with steel plate isolation between each chamber.

Internal Components

Busbars (busbars), circuit breakers, conventional relays, comprehensive relay protection devices, metering instruments, isolating switches, indicator lights, earthing switches, etc.

1. Classification by Circuit Breaker Installation Method

(1) Withdrawable or trolley type:The main electrical components in the cabinet (e.g., circuit breakers) are mounted on extractable trolleys. Trolley switchgear features excellent interchangeability, which greatly improves power supply reliability. Common trolley types include isolating trolley, metering trolley, circuit breaker trolley, PT trolley, capacitor trolley, station service transformer trolley, etc.

(2) Fixed type:All electrical components in the cabinet (e.g., circuit breakers or load switches) are fixedly installed. Fixed switchgear is simpler and more economical.

2. Classification by Installation Location

(1) Indoor use (marked with N):Can only be installed and used indoors.

(2) Outdoor use (marked with W):Can be installed and used outdoors.

3. Classification by Cabinet Structure

(1) Metal-enclosed armored switchgearA metal-enclosed switchgear in which main components (e.g., circuit breakers, transformers, busbars, etc.) are respectively installed in earthed compartments separated by metal partitions.

(2) Metal-enclosed compartmental switchgearSimilar to metal-enclosed armored switchgear, its main electrical components are also installed in separate compartments, but equipped with one or more non-metallic partitions meeting certain protection grades.

(3) Metal-enclosed box-type switchgearSwitchgear with a fully metal-enclosed outer casing.

(4) Open-type switchgearSwitchgear with no protection grade requirements and a partially open outer casing.

 

GGD

Jinneng GGD AC Low-Voltage Power Distribution Cabinet is suitable for AC power distribution systems with a frequency of 50Hz, rated operating voltage of 380V and rated operating current ranging from 1000A to 3150A in power users such as substations, power plants, factories and mines. It is used for energy conversion, distribution and control of power, lighting and power generation & distribution equipment.

Designed in response to the requirements of the Ministry of Energy, numerous power users and design institutes, GGD AC low-voltage power distribution cabinets are a new type of low-voltage distribution panel developed under the principles of safety, economy, rationality and reliability.

The product features high breaking capacity, excellent dynamic and thermal stability, flexible electrical schemes, convenient combination, strong serialization and practicability, novel structure and high protection grade. It can be used as a replacement product for low-voltage switchgear assemblies.

(2) Product Model and Its Meaning

① Ac low-voltage distribution cabinet

② Fixed installation and wiring of electrical components

③ Power distribution cabinet

④ Design serial number: breaking capacity of 15kA, 30kA, 50kA

⑤ Main circuit scheme code

⑥ Auxiliary circuit scheme code

(3) Structural Features

① The enclosure of the GGD AC low‑voltage power distribution cabinet adopts a universal cabinet structure. Its framework is assembled by partial welding of 8MF cold‑formed steel sections, equipped with 20‑module mounting holes, resulting in a high degree of universality.

② The GGD cabinet is fully designed with heat dissipation in mind. Different numbers of heat dissipation slots are provided at the upper and lower ends of the cabinet. When electrical components inside generate heat, the heat rises and is discharged through the upper slots, while cool air is continuously drawn into the cabinet through the lower slots. This creates a natural vertical ventilation path within the enclosed cabinet, achieving effective heat dissipation.

③ In accordance with modern industrial product styling requirements, the overall appearance and sectional dimensions of the GGD cabinet are designed using the golden ratio, making the entire cabinet aesthetically pleasing and innovative in appearance.

④ The top cover of the cabinet can be removed when necessary to facilitate on‑site assembly and adjustment of the main busbars. Lifting eyes are installed at the four corners of the cabinet top for hoisting and transportation.

⑤ The protection degree of the cabinet is IP30. Customers may also select a protection degree between IP20 and IP40 according to their environmental requirements.

GCK

Jinneng electric GCK low voltage withdrawable power switch box is composed of power distribution center (PC) cabinet and motor control center (MCC), suitable for power plants, substations, industrial and mining enterprises and other power users as AC 50Hz, the maximum working voltage up to 660V, the maximum working current up to 3150A distribution system, as a power distribution, for electric energy conversion and distribution control of electric motor control and lighting distribution equipment.

(2) Product Model and Its Meaning

① Enclosed switchgear

② Withdrawable type

③ Use code

④ Main circuit scheme number

(3) Structural Features

① The entire cabinet adopts a modular assembled structure with modulus mounting holes, featuring high universality of parts and components, good applicability and high standardization.

② The upper part of the cabinet is the busbar chamber, the front part is the electrical equipment chamber, and the rear part is the cable entry and exit chamber. Steel plates or insulating plates are used for isolation between chambers to ensure safety.

③ Mechanical interlocks are provided between the doors of the drawer compartments in the MCC cabinet and the operating handles of circuit breakers or disconnectors. The door can only be opened when the handle is in the OFF position.

④ The incoming switches, tie switches and drawers of the MCC cabinet have three positions: service position, test position and disconnected position.

⑤ A busbar bridge can be installed on the top of the switchgear as required for power incoming.

GCS

JInneng GCS low voltage withdrawable switchgear is a type of low-voltage distribution equipment where main electrical components (circuit breakers, transformers, protective devices) are installed in individually withdrawable functional units.

Its rated operational voltage typically does not exceed AC 1000V. Each drawer functions as an independent module that can operate in the "connected" position, be safely moved to the "test/disconnected" position, or be fully withdrawn from the cabinet, enabling maintenance without power interruption and rapid fault recovery.

(2) Product Model and Its Meaning

① Enclosed switchgear

② Withdrawable type

③ Electrical system

④ Auxiliary circuit scheme number

⑤ Main circuit scheme number

(2) Structural Features

① The frame is made of Type 8MF open-section steel. The main frame is provided with Φ9.2mm mounting holes with moduli of E=20mm and 100mm, enabling flexible and convenient frame assembly.

② All functional compartments of the switchgear are isolated from each other, divided into functional unit compartment, busbar compartment and cable compartment, with relatively independent functions.

③ Horizontal busbars are arranged horizontally at the rear of the cabinet to improve the busbar's ability to withstand electrodynamic forces, which is a basic measure to ensure high short-circuit strength of the main circuit.

④ The design of the cable compartment allows convenient cable entry and exit both from the top and bottom.

⑤ The modulus of drawer height is 160mm. Drawers vary only in height dimension, while their width and depth remain unchanged. Drawers of the same functional unit feature excellent interchangeability. The rated current of unit circuits is 400A and below.

Clear markings for positions such as OFF, ON, TEST and WITHDRAWN are provided on the drawer front panels. A mechanical interlocking device is installed in each drawer unit.The drawer unit serves as the main component, supporting both withdrawable and fixed types, which can be mixed and arranged freely as required.

The protection degree of the cabinet is IP30 or IP40, and other grades can also be selected according to user requirements.

MNS

MNS Low‑Voltage Withdrawable Switchgear Assembly (hereinafter referred to as switchgear) is an advanced low‑voltage switchgear developed by referencing and improving foreign MNS series low‑voltage switchgear to meet the development needs of the power industry.This product complies with the national standards GB 7251, VDE 660, ZBK 36001‑89 Low‑Voltage Withdrawable Switchgear Assemblies and the international standard IEC 439.MNS low‑voltage switchgear meets various power supply and distribution requirements and is widely used in various low‑voltage power distribution systems such as power plants, substations, industrial and mining enterprises, buildings, hotels and municipal construction.

(2) Structural Features

① The frame of MNS low‑voltage switchgear adopts a modular structure, and its basic framework is assembled from C‑section steel. All structural parts of the frame are galvanized and firmly connected with self‑tapping locking screws or Grade 8.8 hexagon bolts to form the basic cabinet frame.Together with doors, partitions, mounting brackets, busbars, functional units and other parts corresponding to different schemes, a complete switchgear is assembled.Internal dimensions of the switchgear, component dimensions and compartment dimensions all vary in accordance with the modular system (E = 25 mm).

② Each cabinet of the MNS combined low‑voltage switchgear is divided into three compartments: horizontal busbar compartment (at the rear of the cabinet), drawer compartment (at the front of the cabinet) and cable compartment (at the lower part or front right of the cabinet).Compartments are separated from each other by steel plates or high‑strength flame‑retardant plastic functional boards. Metal plates with ventilation holes are installed between upper and lower drawers to effectively prevent accidents caused by arc flash from faulty switching components or short circuits between busbars and other circuits.

③ The structural design of MNS low‑voltage switchgear can meet various incoming and outgoing wiring schemes: top‑in top‑out, top‑in bottom‑out, bottom‑in top‑out and bottom‑in bottom‑out.

④ Compact design: accommodates more functional units in a smaller space.

⑤ Strong universality of structural parts and flexible assembly. With a modulus of E = 25 mm, the structure and withdrawable units can be combined freely to meet system design requirements.

⑥ Busbars are protected by high‑strength flame‑retardant and high‑insulation plastic functional boards, featuring fault arc resistance, ensuring safe and reliable operation and maintenance.

⑦ The mechanical interlocking mechanisms of various drawer sizes comply with standard specifications, with three distinct positions: connected, test and disconnected, ensuring safety and reliability.

⑧ Adopts standard module design, which can form standard units for protection, operation, switching, control, regulation, measurement, indication and other functions respectively, and can be assembled freely as required.

⑨ The cabinet can be provided with a corresponding protection degree according to different working environment requirements.

MCS

MCS Intelligent Low‑Voltage Withdrawable Switchgear is an advanced product developed by integrating the advantages of other low‑voltage products.It is suitable for three‑phase, four‑wire (five‑wire) power distribution systems with a frequency of 50 Hz / 60 Hz, rated voltage of 380 V, and rated current up to 4000 A, applied in power plants, petrochemical, metallurgy, telecommunications, light industry, textile, high‑rise buildings, as well as other civil, industrial and mining enterprises.In places with a high degree of automation and requirements for computer interfaces, such as large power plants, petrochemical and telecommunication systems, it serves as a low‑voltage distribution device for power distribution, centralized motor control and reactive power compensation in power generation and supply systems.

(2) Structural Features

① The basic frame of the switchgear is assembled from C‑section (or 8MF) open‑section steel, featuring uniform appearance, high precision and excellent drawer interchangeability.

② The MCC cabinet has a width of only 600 mm, providing large usable space to accommodate more functional units and save construction land.

③ Components inside the cabinet can be equipped with various types of switching devices according to different user requirements, ensuring high product reliability.

④ The equipment can reserve automation interfaces, and intelligent modules can also be installed on the switchgear to realize remote signalling, remote measurement and remote control functions.

⑤ Drawer functional units are divided into three types: MCCI, MCCII and MCCIII.

Type MCCI: Drawer width 600 mm, heights of 180 mm, 360 mm and 540 mm. The installable height of each cabinet is 1800 mm. Up to 10 units can be installed by combination according to required drawer sizes. Suitable for motor control centers and feeder circuits with relatively large currents.

Type MCCII: Drawer width 600/2 mm, height of 200 mm. The installable height is 1800 mm. Up to 18 units can be installed. Suitable for units below 100 A.

Type MCCIII: Drawer width 600/2 mm, heights of 180 mm, 360 mm and 540 mm. The installable height is 1800 mm. Up to 20 circuits can be installed. Suitable for units below 100 A.

⑥ Operating mechanism: Each drawer is equipped with a specially designed operating mechanism for switching ON and OFF, with multiple anti‑misoperation functions including mechanical interlocking.Type MCCI drawers are equipped with a four‑position positioning device: DISCONNECTED, TEST, SERVICE and REMOVED, and adopt a racking‑in structure.Type MCCII and MCCIII drawer units are of push‑pull type, equipped with positioning devices and anti‑misoperation functions.

 

Detailed Comparison Table of Four Types of Low-Voltage Switchgear: GGD, GCK, GCS and MNS

Comparison Dimension	Type GGD	Type GCK	Type GCS	Type MNS
	Structure Type	Fixed low-voltage switchgear (no drawers)	Withdrawable (drawer-type) low-voltage switchgear (early domestic type)	Withdrawable (drawer-type) low-voltage switchgear (high-performance domestic type)
Frame Structure	8MF cold-formed steel, partially welded and assembled, no modular assembly	C-type open-section steel, fully assembled, no welding	KS steel/8MF steel, fully assembled	C-type aluminum-zinc coated steel, fully assembled, no welding, surface galvanized/aluminum-zinc coated for anti-corrosion
Modular Standard	Mounting holes with 20mm modulus, no unified modular design	E=25mm (domestic general modulus)	E=20mm (domestic standard modulus)	E=25mm (international standard modulus)
Unit Form	No drawers, all electrical components are fixedly installed in the cabinet and cannot be withdrawn	Drawer-type, minimum drawer unit = 1 module (200mm height)	Drawer-type, minimum drawer unit = 1/2 module (80mm height)	Drawer-type, minimum drawer unit = 1/4 module (50mm height)
Maximum Units/Circuits per Cabinet	Few circuits, ≤ 8	Up to 9 units	Up to 11~22 units	Up to 36 units (double-sided installation)
Drawer Advancement Method	No drawers, no advancement operation required	Rotary racking-in type (wrench operation)	Rotary advancement/manual racking-in, easy to operate	Push-pull/racking-in type, convenient to operate
Drawer Positioning/Interlocking	No drawers, no relevant design	Basic mechanical interlocking, regular positioning	Mechanical interlocking, four-position positioning: OFF/ON/TEST/WITHDRAWN	Complete mechanical interlocking, three-position positioning: Connected/Test/Disconnected, strong anti-misoperation performance
Compartment Design	No strict functional compartments, busbars, components and cables are simply separated without clear division	Three compartments (busbar compartment, drawer compartment, cable compartment), separated by steel plates	Three independent compartments (busbar compartment at the rear, drawer compartment at the front, cable compartment at the bottom), separated by flame-retardant plates	Three compartments + interlayer ventilation isolation plates, busbars protected by flame-retardant functional plates, complete arc flash prevention design
Busbar Arrangement	Horizontal busbars on the top of the cabinet, vertical busbars at the rear	Horizontal busbars arranged on the top of the cabinet, vertical busbars on the side	Horizontal busbars placed horizontally at the rear of the cabinet to enhance electrodynamic resistance; vertical busbars with flame-retardant protection	Horizontal busbars at the rear, vertical busbars flame-retardant and enclosed, strong fault arc resistance
Rated Main Busbar Current	≤ 3150A	≤ 4000A	≤ 4000~6300A	≤ 6300A
Rated Current of Drawer Circuit	Circuit current ≤ 2500A (no drawers, calculated by the whole cabinet circuit)	≤ 630A	≤ 400A (good adaptability for high-current units)	≤ 400A (extremely high density for low-current circuits)
Protection Degree	Default IP30, optional between IP20~IP40	IP30~IP40	IP30~IP40	IP30~IP54, wider range of optional protection degrees
Operation Method	Single-sided operation, maintenance must be powered off, the whole cabinet must be cut off for maintenance	Single-sided operation, drawers can be withdrawn for maintenance with power on	Single-sided operation, drawers can be withdrawn for maintenance with power on	Double-sided operation, double-sided wire entry and exit (cabinet depth 1000mm), maintenance can be carried out with power on, highest operation flexibility
Intelligent Adaptability	No intelligent interface, poor expandability	General intelligence, basically adapted to simple control needs	Easy intelligent expansion, adaptable to various intelligent modules	Complete intelligent interfaces, can be easily connected to computers, adapted to high automation needs
Core Advantages	Lowest cost, simple structure, high reliability, easy maintenance, good dynamic and thermal stability	High cost performance, both for power distribution and motor control (MCC), mature structure, flexible assembly	High circuit density, strong high-current capacity, good dynamic and thermal stability, reliable plug-in, easy intelligent expansion	Highest circuit density, strongest modularization, double-sided operation, good anti-corrosion performance, in line with international standards, complete intelligence
Core Disadvantages	Few circuits, large floor space, unable to maintain with power on, poor expandability, no intelligent interface	Low circuit density, large drawer size, relatively laborious operation, single-sided operation, general intelligence	Only single-sided operation, modulus (20mm) incompatible with international standard (25mm), higher cost than GCK	Highest cost, mainly for low current, less adaptable to high-current units than GCS
Applicable Scenarios	Substations, small factories and mines, civil buildings, simple power distribution, places with low maintenance frequency requirements	Medium and small factories, ordinary motor control centers (MCC), conventional power distribution scenarios	Petrochemical, metallurgy, data centers, power plants, high-rise buildings, high reliability/high automation power distribution systems	Large power plants, petrochemical, telecommunications, airports, transnational projects, high automation/need for computer interfaces, high-density low-current power distribution scenarios
Cost Level	Lowest	Low-Medium	Medium-High	Highest

 

Advantages and Disadvantages of Various Types of Switchgear

Withdrawable switchgear saves space, is convenient for maintenance, has more outgoing circuits, but is expensive; while fixed switchgear has relatively fewer outgoing circuits and occupies more space. If the space provided by the customer is too small to install fixed switchgear, it should be replaced with withdrawable switchgear.

1. GGD AC Low-Voltage Power Distribution Cabinet

This switchgear has the advantages of reasonable structure, convenient installation and maintenance, good protection performance, high breaking capacity, large capacity, strong breaking capacity, strong dynamic stability, and wide applicability of electrical schemes. It can be used as a replacement product.

Disadvantages: Few circuits, units cannot be arbitrarily combined, occupies a large area, and cannot be connected to computers.

2. GCK Switchgear

It has the advantages of high breaking capacity, good dynamic and thermal stability, advanced and reasonable structure, flexible electrical schemes, strong serialization and universality, and arbitrary combination of various scheme units. A single cabinet can accommodate more circuits, save floor space, have a high protection grade, be safe and reliable, and be convenient for maintenance.

Disadvantages: The horizontal busbar is arranged on the top of the cabinet, the vertical busbar is not equipped with flame-retardant plastic functional boards, and it cannot be connected to computers.

3. GCS Low-Voltage Withdrawable Switchgear

It has high technical performance indicators, can meet the development needs of the power market, and can compete with existing imported products. As a new type of low-voltage withdrawable switchgear designed in accordance with the principles of safety, economy, rationality and reliability, it also has the characteristics of high breaking and closing capacity, good dynamic and thermal stability, flexible electrical schemes, convenient combination, strong serialization and practicability, novel structure and high protection grade.

4. MNS Series Switchgear

Compact design, which can accommodate more functional units in a small space. It has strong structural universality and flexible assembly. The C-shaped profiles with a modulus of 25mm can meet the requirements of various structural forms, protection grades and service environments.

It adopts standard module design, which can form standard units for protection, operation, switching, control, regulation, indication, etc. Users can choose and assemble them arbitrarily according to their needs.

High technical performance, with main parameters reaching the contemporary international technical level. It saves space, has a high degree of standardization, serialization and generalization, and can greatly reduce the space for storage, transportation and prefabrication. Convenient assembly, no special complexity required.

5. MCS Low-Voltage Withdrawable Switchgear

The cabinet is assembled from C-section steel, with a uniform appearance, high precision and good drawer interchangeability.

The width of the MCC cabinet is only 600mm, but it has a large usable capacity, which can accommodate more functional units and save construction land.

The components inside the cabinet can be equipped with various types of switches according to different user requirements to better ensure the high reliable operation of the product.

This device can reserve automation interfaces, and modules can also be installed on the switchgear to realize "three remote" functions (remote signaling, remote measurement, remote control) and control equipment.

Disadvantages: High cost.