GCS Low-voltage withdrawable switchgear

GCS low-voltage withdrawable switchgear is suitable for power distribution systems in industries such as power plants, petroleum, chemical, metallurgical, textile, and high-rise buildings.

Overview

GCS low-voltage withdrawable switchgear is suitable for power distribution systems in power plants, petroleum, chemical, metallurgical, textile, and high-rise building industries. In large power plants and petrochemical systems with a high degree of automation and computer interface requirements, it serves as a low-voltage complete power distribution device used in power generation and supply systems with three-phase AC frequency of 50(60)Hz, rated operating voltage of 380V(400V), (660V), and rated current of 4000A or less for power distribution, centralized motor control, and reactive power compensation.

Model and Meaning

Performance Indicators

The design of the device conforms to the following standards: 
IEC439-1 Low-voltage switchgear and controlgear assemblies 
GB7251 Low-voltage switchgear and controlgear assemblies 
ZBK360001 Low-voltage withdrawable switchgear and controlgear assemblies

Basic Parameters

Main Structure

◆ The main frame adopts 8MF type open steel. The two sides of the steel have installation holes with modules of 20mm and 100mm and Φ9.2mm, allowing for flexible internal installation; 
◆ The main frame assembly design offers two options: a fully assembled structure and a partially (side frame and beam) welded structure, allowing users to choose; 
◆ The various functional compartments of the device are isolated from each other. The compartments are divided into functional unit compartments, busbar compartments, and cable compartments. The functions of each compartment are relatively independent; 
◆ The horizontal main busbar adopts a rear-mounted horizontal arrangement to enhance the busbar's anti-electromotive force capability, which is a fundamental measure to ensure the high short-circuit strength of the device's main circuit; 
◆ The design of the cable compartment makes it very convenient for cables to enter and exit from the top and bottom. 
◆ Dimensions of the general-purpose cabinet body (see table below)

Functional Unit

◆ The drawer height module is 160mm. It is divided into five size series: 1/2 unit, 1 unit, 3/2 unit, 2 unit, and 3 unit. The rated current of the unit circuit is 400A or less; 
◆ The drawer only varies in height, while the width and depth remain unchanged. Drawers with the same function have good interchangeability; 
◆ Each MCC cabinet can install up to 11 single-unit drawers or 22 1/2-unit drawers. Drawers of one unit or more use multi-functional rear panels; 
◆ The input and output wires of the drawers use the same specification of plug-in structure with different numbers of pieces according to the current size; 
◆ The connection between the 1/2 unit drawer and the cable compartment uses a backplane structure ZJ-2 type connector; 
◆ The connection between the unit drawer and the cable compartment uses the same size rod-type or tube-type structure ZJ-1 type connector according to the current rating; 
◆ The drawer unit is equipped with a mechanical interlock device.

Main Electrical Components

The selection principle of the main electrical components is based on imported technology, domestic mass production capability, and the ability to meet the high-performance requirements of the device; 
◆ The power supply and feeder unit circuit breaker mainly selects the AH series. Other more advanced Schneider M series and ABB F series can also be selected. The AH circuit breaker has the characteristics of good performance, compact structure, light weight, and strong series. The price is relatively low, maintenance and use are convenient, and various performance indicators can meet the requirements of this device; 
◆ The drawer unit (motor control unit, some feeder units) circuit breaker mainly selects CM1, TG, TM30 series molded case circuit breakers, and some MOELLER NZM-100A series. These switches have good performance, compact structure, short arc or no arc, and high technical and economic indicators, which can meet the requirements of this device; 
◆ Choose Q series for isolating switches and fuse isolating switches. This series boasts high reliability, strong breaking capacity, and mechanical interlocking capability; 
◆ Primarily select NT series fuses; 
◆ Choose B series and LC1-D series AC contactors.

Device Features

◆ Enhancing the thermal capacity of the connecting pieces significantly reduces the additional temperature rise caused by the temperature rise of the connecting pieces to the connectors, cable ends, and partition plates; 
◆ Clear and reliable separation between functional units and compartments ensures that a malfunction in one unit does not affect the operation of other units, limiting the malfunction to the smallest possible scope; 
◆ The horizontally arranged busbars ensure good dynamic and thermal stability of the device, capable of withstanding the impact of 80/176kA short-circuit current; 
◆ The MCC cabinet can accommodate up to 22 circuits per single cabinet, fully considering the needs of large-capacity power generation, petrochemical systems, and automated electric door (machine) groups in various industries; 
◆ The connection between the device and external cables is completed in the cable compartment, and cables can enter and exit from the top and bottom. The current transformer is installed in the cable compartment for convenient installation and maintenance; 
◆ In the same power distribution system, the short-circuit current can be limited by matching the current-limiting reactor, stabilizing the bus voltage at a certain value, and partially reducing the requirements for the short-circuit strength of components; 
◆ The drawer unit has a sufficient number of secondary connectors (32 pairs for 1 unit or more, 20 pairs for 1/2 unit), meeting the requirements for the number of connection points for computer interfaces and automatic control circuits.

Auxiliary Circuit

The design of the auxiliary circuit diagram complies with the relevant design technical regulations, such as "Technical Regulations for the Design of Plant Power Supply in Thermal Power Plants." It is suitable for low-voltage plant (station) power supply systems in power plants and substations, as well as low-voltage power distribution systems in factories, mines, and high-rise buildings. 
The auxiliary circuit scheme is designed based on the main circuit scheme, dividing the power supply lines, feeders (PC), and motor feeders (MCC) into functional units for operation control.