Medium-voltage switchgear is designed with modular and metal-enclosed structures, featuring a three-compartment layout for enhanced safety and functionality. Its assembly process involves meticulous component preparation, precise cabinet and internal component installation, and rigorous inspection and testing. The production line includes material storage, sheet metal processing, assembly, testing, and packaging areas, ensuring high-quality output. Comprehensive testing covers design checks, resistance measurement, withstand voltage tests, mechanical operations, and insulation verification. This streamlined process guarantees reliability and safety, meeting industry standards for medium-voltage applications.

Detailed Introduction of Medium-Voltage Switchgear

I. Structural Characteristics

Structural Table

No.	Component Name	Function Description	Material	Notes
1	Cabinet	The main structure of the switchgear, used for installing and fixing other components.	Zinc-aluminum alloy steel plate	The surface coating consists of 55% aluminum, 43.4% zinc, and 1.6% silicon, solidified at high temperature.
2	Circuit Breaker Compartment	Installation of circuit breakers for circuit control.	–	–
3	Busbar Compartment	Installation of busbars for power transmission.	–	–
4	Cable Terminal Compartment	Connection of cables for power distribution.	–	–
5	Low-Voltage Compartment	Installation of control and protection devices.	–	–
6	Live Door	Isolation of high-voltage components to ensure operational safety.	–	–
7	Circuit Breaker	Control of circuit connection and disconnection.	–	–
8	Secondary Plug	Connection of the secondary circuit.	–	–
9	Main Busbar	Power transmission.	–	–
10	Busbar Insulator	Insulation and support of busbars.	–	–
11	Ground Switch	Ground protection.	–	–
12	Static Contact Box	Coordination with the moving contacts of the circuit breaker.	–	–
13	Support Insulator	Support and insulation.	–	Optional with live display device.
14	Insulating Partition	Isolation of different functional areas.	–	–
15	Cable Connection Terminal	Connection of cables.	–	–
16	Panel Heater	Prevention of condensation.	–	–
17	Current Transformer	Measurement of current.	–	–
18	Pressure Relief Panel	Pressure relief to ensure equipment safety.	–	–

Detailed Description

1. Modular Design

• The medium-voltage switchgear adopts a modular structure, which can be flexibly configured according to different requirements and is convenient for expansion. Each functional unit, such as the circuit breaker compartment, busbar compartment, and cable compartment, is independently designed and can be easily combined to meet various requirements.
• This modular design also facilitates the maintenance and replacement of individual components without affecting the entire system.

1. Metal-Enclosed Structure

• The switchgear is typically enclosed in a metal cabinet, which can effectively prevent interference from external factors such as dust, moisture, and small animals, ensuring the reliability and safety of the internal electrical components.
• The cabinet is usually made of high-quality steel or aluminum alloy, with high mechanical strength and corrosion resistance.

1. Three-Compartment Layout

• The switchgear usually adopts a three-compartment layout, including the main switch compartment, busbar compartment, and cable compartment. This layout separates the high-voltage components and the control components, reducing the risk of electrical short circuits and improving the safety of operation and maintenance.
• The compartments are interconnected through insulated busbars or connectors, ensuring reliable electrical connections while maintaining a clear separation of functions.

1. Insulation and Arc Protection

• The internal components of the switchgear are designed with high insulation performance to ensure safe operation at medium-voltage levels. Insulating materials such as epoxy resin, SF6 gas, or vacuum are commonly used to provide effective insulation between live parts.
• Arc protection measures are also incorporated, such as arc shields and arc extinguishing devices, to prevent arc faults from causing damage to the equipment and personnel.

II. Assembly Process

Process Table

No.	Process Name	Process Content	Equipment	Labor Hours Quota	Process Equipment
1	Material Preparation	Preparation of all components.	Material transport vehicle	–	–
2	Contact Box Assembly	Installation of contact boxes and related components.	Wiring rack	–	Elevating platform
3	Cabinet Assembly	Assembly of cabinet components.	Cabinet assembly jig	–	Material placement table
4	Electrical Connection	Connection of main and secondary circuits.	–	–	–
5	Inspection and Adjustment	Inspection of assembly quality and adjustment of components.	–	–	–

Detailed Description

1. Component Preparation

• All necessary components, including switchgear cabinets, circuit breakers, busbars, insulators, control devices, and accessories, are carefully inspected and prepared. Any damaged or defective parts are replaced to ensure the quality and reliability of the final product.
• These components are usually pre-fabricated in a controlled environment to ensure precision and consistency.

1. Cabinet Assembly

• The metal enclosure of the switchgear is assembled first. The frame and panels are welded or bolted together to form a rigid structure. The enclosure is then painted or coated with a protective layer to enhance its corrosion resistance.
• The compartments within the enclosure are partitioned using insulated panels or barriers to create separate spaces for different functions.

1. Installation of Internal Components

• The busbars are installed first, ensuring proper alignment and secure connections. The busbars are usually made of high-conductivity copper or aluminum and are insulated to prevent electrical leakage.
• Circuit breakers and other switching devices are mounted in their designated compartments. These devices are carefully aligned and connected to the busbars through insulated connectors.
• Control devices, such as relays, meters, and protection devices, are installed in the control compartment. Wiring is done according to the electrical schematics, ensuring correct connections and proper labeling.

1. Inspection and Testing

• After the assembly is complete, a thorough inspection is conducted to check for any loose connections, incorrect wiring, or misaligned components.
• The switchgear is then subjected to various tests, including insulation resistance testing, dielectric withstand testing, and functional testing of the circuit breakers and control devices. These tests ensure that the switchgear meets the required safety and performance standards.

III. Production Line

Production Line Layout

1. Material Storage and Preparation Area

• This area is used for storing metal sheets, insulating materials, and components. The materials are organized and prepared for use in the production process.
• Quality control checks are performed on incoming materials to ensure they meet the specified standards.

1. Sheet Metal Processing Section

• Metal sheets are cut, bent, and welded to form the enclosure and internal structures of the switchgear. Advanced sheet metal processing equipment, such as laser cutting machines and press brakes, are used to ensure precision and efficiency.
• The processed metal parts are then sent to the painting or coating section for surface treatment.

1. Component Assembly Line

• This is the main area where the switchgear is assembled. The metal enclosures are placed on assembly stations, and components are installed in a sequential manner.
• Assembly workers follow detailed work instructions and use specialized tools to ensure proper installation of each component.

1. Testing and Inspection Station

• After assembly, the switchgear is moved to the testing and inspection station. Here, technicians perform the necessary tests to verify the performance and safety of the equipment.
• Any defects or issues identified during testing are corrected before the switchgear is approved for packaging and shipping.

1. Packaging and Shipping Area

• The final products are packaged in protective cases or crates to prevent damage during transportation. Shipping labels and documentation are attached, and the packaged switchgear is stored in a warehouse or loaded onto transport vehicles for delivery to customers.

Assembly Testing Table

No.	Test Item	Test Content	Testing Equipment	Testing Standard	Notes
1	Design Inspection	Check whether the electrical circuit and mechanical structure design meet the requirements.	–	Complies with design drawings	–
2	Main Circuit Resistance Measurement	Measure the resistance of the main circuit to ensure it meets the standard.	Resistance tester	Complies with standard	–
3	Power Frequency Withstand Voltage Test	Conduct power frequency withstand voltage tests on the main and secondary circuits.	Withstand voltage tester	Complies with standard	–
4	Mechanical Operation Test	Test the mechanical operation of circuit breakers and draw-out units.	–	Operation is smooth	–
5	Secondary Circuit Inspection	Check the connections of the secondary circuit.	–	Connections are correct	–
6	Insulation Test	Conduct insulation tests on the main cables and secondary circuits.	Insulation tester	Complies with insulation standards	–
7	Five-Prevention Function Test	Test the five-prevention functions of the switchgear.	–	Complies with five-prevention requirements	–
8	Mechanical Interlock Function Test	Test the mechanical interlock function.	–	Interlock is reliable	–

The above content combines the detailed structural characteristics, assembly process, and production line of medium-voltage switchgear, as well as the structural table, process table, and assembly testing table, to comprehensively demonstrate the production process and quality control of medium-voltage switchgear.