Overview of basic knowledge and application technology of Electrical system cabinet

The classification dimensions of Outdoor electrical cabinets are diverse and can be mainly classified into the following categories: According to voltage levels, it can be divided into low-voltage cabinets (rated voltage AC 1000V and below), medium voltage cabinets (rated voltage 3.6kV to 40.5kV), and high-voltage cabinets (rated voltage 72.5kV and above). There are significant technical differences in insulation coordination, safety distance, and protection level among cabinets with different voltage levels.

Divided by functional positioning, it mainly includes incoming cabinets, distribution cabinets, control cabinets, frequency conversion cabinets, generator control cabinets, etc. The incoming cabinet is responsible for receiving and initially distributing electrical energy; The distribution cabinet realizes multi circuit power distribution; The control cabinet is used for the start stop control of electric motors or other electrical equipment; The frequency conversion cabinet is specifically designed for AC speed regulation systems; The generator set control cabinet is used for automatic switching and management of backup power supply.

Outdoor weatherproof enclosure cabinet boxes can be divided into fixed, pull-out (handcart), modular, and frame structures according to their structural forms. Fixed structure is simple and cost-effective; Pull out type is easy to maintain and repair, with high reliability; Modular design facilitates flexible configuration and expansion; The framework structure is suitable for large capacity and customized needs.

The technical functions of an Electrical system cabinet are mainly reflected in three aspects: Energy distribution function: Scientifically distribute the incoming power supply to each feeding circuit through the busbar system, meet the energy requirements of different loads, ensure three-phase load balance, and reduce line losses.

Protection function: Equipped with comprehensive protective appliances, in the event of system overload, short circuit, grounding, undervoltage and other faults, it can accurately operate according to the principle of selective protection, timely cut off the faulty circuit, minimize the power outage range, and ensure personal and equipment safety.

Control function: Control cabinet enclosures and enclosures realize the connection, disconnection, adjustment, and status monitoring of circuits, support local and remote operations, and can integrate automation control logic to enhance the intelligent level of system operation.

The Electrical cupboard consists of the following core components:Cabinet structure: As the main load-bearing and protective body, it is usually made of cold-rolled steel plate through CNC machining, electrostatic spraying and other processes. Must meet the specified protection level (IP code), mechanical strength, corrosion resistance, and fire resistance performance. The cabinet design should fully consider heat dissipation, electromagnetic shielding, and internal arc fault protection.

Electrical components: including circuit breakers, isolating switches, contactors, fuses, current transformers, voltage transformers, lightning arresters, relays, etc. The selection of components should comply with relevant national standards, have sufficient breaking capacity, electrical and mechanical life, and meet the requirements for system short-circuit current calculation.

Secondary system: composed of measuring instruments, indicator lights, control buttons, conversion switches, protective devices, and wiring terminals. Modern Electrical cabinet outdoor systems widely adopt intelligent measurement and control units to achieve real-time collection, display, recording, and communication transmission of electrical parameters, supporting remote monitoring and fault diagnosis.

Conductive and connection system: including main busbar, branch busbar, insulation support components, and secondary wiring. The material of the busbar is usually copper or aluminum, and the selection of the cross-section requires current carrying capacity calculation and dynamic thermal stability verification. The wiring should be standardized, clear, and easy to maintain and repair.

The reasonable selection of Switching cabinet is the foundation for ensuring the safe and economical operation of the system, and the following factors need to be comprehensively considered:

Technical parameter matching: Core parameters such as rated voltage, rated current, rated frequency, and short-circuit withstand strength should be adapted to the actual operating conditions of the system, and appropriate development margins should be reserved.

Environmental adaptability: Select the appropriate protection level and measures based on the environmental conditions of the installation site (altitude, temperature, humidity, pollution level, corrosive gases, etc.). Special environments such as high altitude, high humidity, and high corrosion require targeted design.

Reliability and lifespan: Evaluate the mechanical lifespan, electrical lifespan, and maintenance free period of Electrical enclosure cabinets and key components, and prioritize the selection of products with mature technology, rich operating experience, and stable quality.
Economic rationality: Taking into account initial investment, operational losses, maintenance costs, and full life cycle expenses, conduct technical and economic comparisons to avoid sacrificing reliability and safety in pursuit of low costs.

Standardization and scalability: Priority should be given to selecting products that comply with current national and industry standards to facilitate spare parts supply and operation and maintenance management. The design should consider the possibility of future load growth and functional expansion.

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