I. What is a switch cabinet?
A switchgear is an electrical device in which external power lines first enter the main control switch inside the cabinet, and then enter the branch control switches, with each branch circuit configured according to its needs. It is an assembly consisting of one or more low-voltage switchgear devices and related control, measurement, signaling, protection, and regulation equipment, all internally connected by the manufacturer using structural components. The main function of a switchgear is to open, close, control, and protect electrical equipment during power generation, transmission, distribution, and energy conversion in a power system. The main components inside a switchgear include circuit breakers, disconnect switches, load switches, operating mechanisms, instrument transformers, and various protective devices.
II. Structure and Composition Classification of Switchgear
To protect personal and equipment safety, the switchgear is divided into several compartments using different compartment classification methods:
Busbar compartment: includes horizontal busbar compartment and vertical busbar compartment functional unit compartment (switchover compartment).
Cable outlet room: includes cable room and secondary equipment room
2.1 Main Components of Switchgear
Cabinet: The outer frame of the switchgear and its internal mounting and support components.
Busbar: A low-impedance conductor that can be connected to several circuits separately.
Functional unit: All electrical equipment and mechanical components (including incoming and outgoing units) that perform the same function.
2.2 Incoming Line (Plug-in Busbar Trunking or Cable) Method
Top entry line; bottom entry line; side entry line; rear entry line
2.3 Outgoing cable method (plug-in busbar or cable)
Front-mounted cables (top or bottom) can be wall-mounted.
Rear-outlet cables (top or bottom) cannot be installed against a wall.
2.4 Classification of busbars:
Main busbar (horizontal busbar): A busbar that connects one or more distribution busbars and/or incoming and outgoing line units.
Distribution busbar (vertical busbar): A busbar within the frame unit that connects to the main busbar and supplies power to the outgoing units.
Composition of switch cabinet
2.5 Functional Unit Classification
Fixed type: The main circuit connection can only be made and disconnected when the switch cabinet is powered off.
Portable (fixed-separation): It can be safely disconnected or connected to the main circuit even when the main circuit is energized, and has both connection and relocation positions.
Extractable type: It can be safely disconnected or connected from the main circuit even when the main circuit is energized, and has the functions of connection, testing, separation, and removal.
2.6 Installation Method
Installation location classification: Indoor installation; Outdoor installation
Installation methods are categorized as: wall-mounted; off-wall mounted.
Fixing methods can be categorized as follows: bolt fixing; electric welding fixing.
III. Classification of Low-Voltage Switchgear
3.1 GCS Cabinet:
GCS type low-voltage withdrawable switchgear is used in three-phase AC power supply systems with a frequency of 50Hz, a rated operating voltage of 400V (690V), and a rated current of 4000A and below, for power distribution, centralized control of motors, and capacitor compensation. It is widely used in power plants, petroleum, chemical, metallurgical, textile, and high-rise buildings, and can also be used in large power plants, petrochemical systems, and other locations requiring high levels of automation and computer interface.
3.2GCK cabinet: (MCC)
The GCK low-voltage withdrawable switchgear (hereinafter referred to as switchgear) consists of two parts: a power distribution center (PC) cabinet and a motor control center (MCC). This device is suitable for AC 50 (60) Hz, rated operating voltage less than or equal to 660V, and rated current of 4000A and below, and is used as a power distribution, motor control and lighting distribution equipment.
3.3MNS Cabinet: (MCC)
The MNS type low-voltage withdrawable switchgear (hereinafter referred to as switchgear) is an advanced low-voltage switchgear developed to meet the needs of the power industry. It is designed and improved based on the foreign MNS series low-voltage switchgear. This product complies with national standards GB7251, VDE660 and ZBK36001-89 "Low-voltage withdrawable switchgear". International standard IEC439 stipulates that the MNS type low-voltage switchgear is suitable for various power supply and distribution needs and can be widely used in power plants, substations, industrial and mining enterprises, buildings, hotels, municipal construction and other low-voltage power distribution systems.
3.4GGD cabinet: (ESS)
The GGD type AC low-voltage distribution cabinet is suitable for AC 50Hz power distribution systems of power users such as substations, power plants, factories and mines, with a rated operating voltage of 380V and a rated operating current of 1000-3150A. It is used for power conversion, distribution and control of power, lighting and power generation and distribution equipment.
3.5PGL cabinet:
The PGL type AC low-voltage switchgear is suitable for power plants, substations, industrial and mining enterprises, and other power users for power conversion, distribution, and control of power, lighting, and electrical equipment in AC 50Hz power distribution systems with a rated operating voltage of 380V and a rated current up to 2500A. This product has high breaking capacity, with a rated short-time withstand current of up to 50kA.
PGL type AC low-voltage distribution panel is divided into: low-voltage metering cabinet, low-voltage incoming line cabinet, capacitor compensation cabinet, mains-generator conversion cabinet, busbar interconnection cabinet, and low-voltage outgoing line cabinet.
PGL cabinet
IV. Differences between GCS, GCK, MNS, and GGD switchgear
GGD refers to a fixed cabinet, while GCK, GCS, and MNS refer to a drawer cabinet.
The drawer push-in mechanisms of GCK cabinets and GCS and MNS cabinets are different;
GCS cabinets can only be made as single-sided control cabinets, with a depth of 800mm.
MNS cabinets can be made into double-sided operating cabinets with a depth of 1000mm.
Advantages and disadvantages of various switchgear models
Generally speaking: withdrawable cabinets save space, are easy to maintain, and have more outgoing circuits, but are more expensive; while fixed cabinets have fewer outgoing circuits and take up more space. If the customer provides too little space to install a fixed cabinet, a withdrawable cabinet should be installed instead.
GGD type AC low-voltage switchgear: This switchgear has the advantages of reasonable structure, convenient installation and maintenance, good protection performance, high breaking capacity, large capacity, strong sectionalizing ability, 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 and occupy a large area, and cannot communicate with computers.
GCK switchgear features high breaking capacity, good dynamic and thermal stability, advanced and reasonable structure, flexible electrical schemes, strong series compatibility and versatility, and arbitrary combination of various scheme units. A single cabinet can accommodate a large number of circuits, saving floor space, offering high protection levels, safety and reliability, and convenient maintenance.
Disadvantages: The horizontal busbar is located on the top of the cabinet, the vertical busbar lacks a flame-retardant plastic functional panel, and it cannot communicate with the computer.
GCS low-voltage withdrawable switchgear: Possesses high technical performance indicators, adapts to the needs of the power market development, and can compete with existing imported products. Designed based on the principles of safety, economy, rationality, and reliability, this new type of low-voltage withdrawable switchgear also features high breaking and making capacity, good dynamic and thermal stability, flexible electrical schemes, convenient combination, strong series applicability, novel structure, and high protection level.
Disadvantages: The contact between the moving and stationary contacts is not tight, which can easily lead to overheating, eddy currents, and loosening.
Advantages of MNS series products:
Compact design: It can accommodate more functional units in a smaller space.
With strong structural versatility and flexible assembly: C-shaped profiles with a 25mm module can meet the requirements of various structural forms, protection levels and usage environments.
It adopts a standard modular design: it can be composed of standard units such as protection, operation, conversion, control, regulation, and indication, and users can choose and assemble them arbitrarily according to their needs.
It boasts advanced technical performance. Its main parameters have reached the contemporary international technical level.
Compact space requirements. High degree of standardization and modularization significantly reduces the space needed for storing and transporting prefabricated components.
It is easy to assemble and does not require special complexity.
Advantages and disadvantages of various switchgear models
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