Design of New-Type Power Distribution Cabinets

In modern electrical engineering, distribution cabinets and distribution boxes serve as the "nerve centers" for power distribution and control. Their design quality directly determines the safety, reliability, and cost-effectiveness of the entire power supply system. With increasingly complex power demands and rising levels of intelligence, the design of distribution equipment has evolved from simply "housing electrical components" into a comprehensive systems engineering task integrating structural mechanics, electromagnetic compatibility, thermal management, human-machine interaction, and intelligent control. This article will explore optimization design strategies for high-voltage/low-voltage distribution cabinets and distribution boxes from a design perspective.

I. High-Voltage/Low-Voltage Distribution Cabinets: Optimization of System-Level Design

High-voltage/low-voltage distribution cabinets are the core equipment in distribution rooms. Their design must achieve an optimal balance between reliability, practicality, and economy.

• Structural Design: Modularity and Maintainability

• Drawer-Type/Withdrawable (e.g., KYN28) Design: This is currently the mainstream high-reliability design. By       mounting key components like circuit breakers on withdrawable       "drawers" or "trucks," it enables safe       "maintenance under de-energized conditions." The design must precisely       consider track and floor levelness to ensure smooth movement of the       truck. Vibration damping is achieved by laying insulating rubber mats,       reflecting the coordination between structural design and civil       construction.

• Spatial Layout and Compartmentalization: Cabinets like the KYN28 use metal partitions to divide the       cabinet into separate compartments (e.g., cable chamber, truck chamber,       busbar chamber, instrument compartment), achieving functional zoning and       electrical isolation, which effectively prevents fault propagation. The       layout must be precisely designed based on component dimensions, heat       dissipation requirements, and electrical safety clearances.

• Low-Voltage Drawer-Type Design (e.g., GCS, MNS): These low-voltage cabinets utilize drawer units,       significantly improving maintenance efficiency. The design must consider       the mechanical interlocking of drawers, the strength of rails, and the       reliability of connectors to ensure stable electrical connections despite       frequent plugging/unplugging.

• Component Selection and Protection Function Design

• Protection Strategy: The       core of the design lies in configuring protection functions. Fuses are       low-cost but are only suitable for short-circuit protection and require       replacement. Vacuum circuit breakers or SF6 circuit breakers, however,       provide comprehensive overload and short-circuit protection and are       reusable, making them the preferred choice for complex loads. The       selection of protection components should be based on load       characteristics (e.g., motors, lighting, electronic equipment).

• Intelligent Integration:       Traditional relay-based protection systems are complex and have high       failure rates. The modern design trend is to integrate intelligent       multifunctional protection relays. These devices combine measurement,       protection, control, and communication functions into one unit,       simplifying secondary circuits, improving system reliability, and       providing interfaces for future connection to Energy Management Systems       (EMS) or Building Automation Systems (BAS).

• Economic and Practical Design

• Domestic vs. Imported Trade-off: Domestic cabinets (e.g., GCS) offer moderate prices and       convenient after-sales service but often have a larger physical       footprint. Imported cabinets (e.g., ABB's MNS) feature advanced       technology and a compact size but come with higher costs and potentially       longer repair cycles. Designers need to make a comprehensive choice based       on project budget, distribution room space, and maintenance capabilities.

• Parametric Design:       Precise calculation of the main busbar's maximum rated current and       short-time withstand current is essential. Based on these calculations,       appropriate busbar specifications and the cabinet's Ingress Protection       (IP) rating must be selected to ensure safe operation even under peak       load conditions.

II. Distribution Boxes: Design Focused on Detail and Innovation

As the endpoints of power distribution, distribution box design focuses more on installation convenience, environmental adaptability, and user experience.

• Installation Method Design

• Surface-Mounting vs. Flush-Mounting: Surface-mounted distribution box design (e.g., using angle       steel brackets or metal expansion bolts) must consider wall load-bearing       capacity and precise positioning of fixing points. Flush-mounted       distribution boxes require close coordination with civil construction to       ensure accurate dimensions and levels of pre-formed openings, and to       prevent contamination of the box during subsequent plastering, demanding       highly accurate design drawings.

• Structural and Material Innovation Design

• Patent Design Example:

• Strength and Stability: Adding raised ribs on the inner side of the door and        corresponding grooves on the door frame creates a        "mortise-and-tenon" like structure when closed, significantly        enhancing door stiffness and overall stability, solving the common issue        of deformation in traditional sheet metal doors.

• Noise Reduction Design: The inner walls incorporate an aluminum foam layer with        round holes. Aluminum foam is a lightweight, porous material whose        internal micropores convert sound waves into heat, effectively absorbing        and eliminating operational noise, creating a quieter environment.

• Energy Efficiency and Precise Control: Internal integration of filter compensation circuits (harmonic      filtering + power factor correction) not only eliminates grid harmonics      but also improves the power factor, directly reducing line losses.      Simultaneously, independent current and voltage detection circuits provide      precise energy consumption data for the system, facilitating subsequent      energy efficiency analysis and optimization.

• Safety and Maintenance Design

• Insulation and Testing: The       design must include an insulation testing procedure. After installation,       a 500V megger (insulation resistance tester) must be used to test       insulation resistance between phases, phase-to-earth, phase-to-neutral,       etc., ensuring it meets standards. This is fundamental for ensuring       personnel and equipment safety.

• Heat Dissipation Design:       Louvers are incorporated into the back panel for heat dissipation, but       this must be coordinated with noise reduction design. This patent design       effectively utilizes efficient aluminum foam sound absorption, allowing       for ventilation openings without causing significant noise leakage,       cleverly resolving the conflict between heat dissipation and noise       reduction.