Online Consultation The processing of electrical cabinets involves multiple requirements such as structural strength, electrical installation convenience, protective performance (such as dust prevention, moisture resistance, heat dissipation), and safety. Improper handling of details may lead to equipment failure, installation difficulties, or safety hazards. The following are the key details that need to be paid attention to during the processing of electrical cabinets:
1、 Cabinet structure design and material selection
1. Material strength and protection level
Material selection:
The main frame is preferably made of cold-rolled steel plate (SPCC, thickness 1.2-2.0mm) or stainless steel (304/316, thickness 1.5-2.5mm) to ensure structural strength; The door and side panels can be appropriately thinned (0.8-1.2mm) to reduce weight.
Stainless steel or carbon steel coated with anti-corrosion treatment should be used outdoors or in humid environments, with a protection level of IP54 or above (dustproof and splash proof).
Pre treatment of sheet metal:
Before cutting, check the flatness of the board, remove surface rust and oil stains, and passivate stainless steel to prevent corrosion.
2. Framework structure design
Modular design:
Adopting an assembled frame (such as welded profiles or bolted connections) for easy transportation and on-site assembly; Internally reserved standardized installation columns (such as TS35 guide rails, U-hole mounting plates), suitable for various electrical components (circuit breakers, contactors, etc.).
Strengthening reinforcement and support design:
When the depth of the cabinet is ≥ 800mm, horizontal reinforcement bars (such as rolled edges or angle steel welding) should be added to the side and back panels to prevent deformation of the cabinet; The top and bottom are designed with load-bearing beams to support the weight of electrical components.
2、 Cutting and drilling details
1. Precise positioning and size control
Hole position accuracy:
The installation holes for electrical components (such as circuit breaker installation holes and guide rail fixing holes) need to be accurately machined according to the drawings, with an error of ≤± 0.5mm; CNC punching machines or laser cutting are used to ensure consistent hole positions.
Example: The spacing between TS35 guide rail installation holes must strictly match the guide rail specifications (such as 60mm, 120mm spacing) to avoid component installation misalignment.
Outlet hole design:
Reserve cable entry holes at the bottom or side, which should match the cable specifications (such as φ 20~φ 100mm), and be equipped with rubber sealing rings or metal wire protection rings to prevent cable wear and dust intrusion.
When multiple cables are fed in, a porous combination or modular feeding board can be designed for easy expansion in the later stage.
2. Surface treatment and deburring
Incision treatment:
After cutting, burrs and slag need to be thoroughly removed, and the edges can be processed with a grinder or chamfering machine (chamfering angle of 30 °~45 °) to avoid scratching the operator or cable insulation layer.
Stainless steel cuts need to be acid washed and passivated, while carbon steel cuts need to be sprayed with anti rust primer to prevent corrosion.
3、 Bending and assembly process
1. Bending angle and rebound control
Door panel bending:
Reserved installation slots for sealing strips (usually 5-8mm deep and 8-12mm wide) should be reserved around the bending of the door panel to ensure a tight seal when closed; The bending angle should be controlled at 90 °± 1 ° to avoid deformation or loose closure of the door panel due to rebound.
Frame assembly:
The columns and beams are bent at right angles and welded or bolted together. During welding, verticality must be ensured (error ≤ 1mm/m), and countersunk holes or protrusions must be reserved for bolted connections to avoid internal protrusions affecting component installation.
2. Sealing and protection design
Sealing strip installation:
EPDM rubber sealing strip (with self-adhesive backing) should be pasted at the contact between the door panel and the cabinet, and the cross-sectional shape can be selected as P-type, D-type or K-type to ensure a complete sealing surface is formed after closure.
Example: Outdoor cabinets need to add rainproof eaves on the outside of the sealing strip, and drip troughs should be designed at the edges of the door panels to prevent rainwater from seeping in.
Heat dissipation and ventilation:
Heat dissipation holes should be opened on the top or side of the cabinet, and the holes should be equipped with dust-proof nets (grid density ≥ 100 mesh) and rainproof louvers. The ventilation area should be calculated based on the heat generation of internal components (usually 50cm ² ventilation area is configured for every 100W power).
In high heat scenarios (such as frequency converter cabinets), a forced ventilation system should be designed, and axial fans (with protective nets) should be installed. The position of the fan should avoid direct blowing of components that may cause dust accumulation.
4、 Welding and surface treatment
1. Welding process control
Internal welding requirements:
Continuous welding or segmented welding (with an interval of 50-100mm and a weld length of 20-30 mm) should be used for frame welding to ensure strength; The internal installation bracket needs to be fully welded and fixed to avoid loosening.
The stainless steel cabinet adopts argon arc welding, with a current of 80~120A and a speed of 4~6mm/s. The weld seam needs to be polished flat and acid washed to prevent weld spot corrosion.
Post weld treatment:
Remove welding slag and spatter, correct the deformed parts (such as mechanical leveling or flame leveling), and ensure that the diagonal error of the cabinet is ≤ 2mm (when the cabinet size is greater than 1000mm).
2. Spraying and rust prevention
Pre processing procedure:
Carbon steel parts need to go through the process of "degreasing → rust removal → phosphating → water washing → drying", with a phosphating film thickness of 1-3 μ m to enhance coating adhesion.
Spray coating process:
Using electrostatic powder spraying, the coating thickness is 80-100 μ m, the color is usually RAL7035 (light gray) or RAL9005 (black), the curing temperature is 180-200 ℃, and the insulation time is 20-30 minutes.
After spraying, check the surface flatness and ensure that there are no bubbles, sagging, or missed spraying, especially inside the installation holes to ensure coating coverage.
5、 Electrical installation coordination details
1. Grounding and lightning protection design
Grounding system:
An independent grounding copper bar (with a cross-sectional area of ≥ 30mm ²) should be installed at the bottom of the cabinet, which should be reliably connected to the cabinet frame through galvanized bolts (the bolts should be equipped with spring washers to prevent loosening); Use braided copper tape to cross connect the cabinet door and body, ensuring that the grounding resistance is less than 4 Ω.
Outdoor cabinets need to be equipped with lightning rods (height ≥ 300mm) at the top and connected to the cabinet grounding system.
Component layout:
Plan the installation positions of components according to the electrical schematic diagram. High current components (such as circuit breakers and contactors) and weak current components (such as PLCs and relays) should be arranged in zones with a spacing of ≥ 100mm to reduce electromagnetic interference.
The installation of the guide rail should be horizontal, with an error of ≤ 1mm/m. The installation height of the components should be easy to operate (such as the center of the circuit breaker handle being 1.2-1.5m above the ground).
2. Cable management
Wire trunking and terminal block:
Install plastic cable trays (width 25~100mm) inside the cabinet for organizing signal and power lines; The terminal block needs to be fixed on an independent installation board, with a distance of ≥ 50mm between the strong and weak electrical terminals.
Cable imports and exports must be labeled with numbers, and identification tags should be hung at both ends of the cable for easy recognition during maintenance.
Shielding and anti-interference:
The signal line needs to use shielded cables, with the shielding layer grounded at one end (usually on the control cabinet side); When the power line intersects with the signal line, it should be laid vertically to avoid interference caused by parallel wiring.
6、 Other key details
1. Safety protection design
Door lock and handle:
Cabinet doors need to be equipped with anti misoperation locks (such as three-point locks), and outdoor cabinets need to be equipped with rainproof lock covers; The handle design should comply with ergonomics and have a non slip surface treatment.
Warning signs:
Warning labels such as "High Voltage Danger" and "Do Not Touch" should be prominently posted on the cabinet, and outdoor cabinets should be labeled with protection level (such as IP55) and electrical schematic index.
2. Packaging and Transportation
Seismic protection:
Components in the cabinet are fixed with foam board or bubble film to prevent shaking during transportation; The cabinet is fixed around with wooden pallets and wrapped with waterproof film externally.
Transport size:
Large cabinets (height>2000mm) need to be split into frames and door panels for transportation and assembled on-site to avoid being unable to pass through the doorway due to height limitations.
summary
The core of electrical cabinet processing is the balance of functionality, safety, and protection, which requires refinement of the process from dimensions such as structural strength, electrical installation convenience, and environmental adaptability (such as temperature and humidity, dust). Key processes such as drilling accuracy, sealing design, and grounding reliability need to be verified through first piece testing and functional testing (such as insulation testing and protection level testing) to ensure that the finished product meets national standards (such as GB 7251.1-2013 "Low Voltage Switchgear") and usage scenario requirements.
