Welding of the back panel of the distribution box

The back panel of a distribution box should be welded with uniform, smooth seams on a steel plate of at least 3 mm thickness, ensuring structural integrity, proper grounding, and compliance with safety standards.

Material and Panel Requirements

The back panel should be made of cold-rolled steel with a minimum thickness of 3 mm to provide sufficient strength and durability . Other materials like stainless steel or aluminum can be used depending on environmental conditions, but welding techniques must be adjusted for heat conductivity and corrosion resistance . The panel edges and openings should be flat, smooth, and free of burrs or cracks to ensure proper fit and sealing .

Welding Techniques

• Seam quality: Welding seams must be uniform and smooth, without welding skin, air holes, or incomplete penetration .
• Lug attachment: Two lugs, typically made from 40x4 mm flat steel and 10 cm long, are welded at the lower left and upper right corners of the back panel for mounting and structural support .
• Joint design: Ensure proper panel fit-up and joint alignment to prevent warping during welding, especially for larger enclosures .
• Welding methods: Common methods include MIG, TIG, or spot welding, chosen based on material type and thickness .

Assembly and Safety Considerations

• Bolt connections: Use flat and spring washers with 2–5 threads exposed to secure components without compromising the weld .
• Grounding: Proper bonding and grounding of the back panel are essential to reduce EMI and ensure electrical safety. Remove paint or non-conductive coatings around mounting points and use star washers or copper braid connections to the central ground bus .
• Sealing: Reserved inlet and outlet holes should have sealing accessories to meet three-level sealing requirements after assembly .

Quality Checks

• Inspect welds for uniformity, penetration, and absence of defects.
• Verify that the panel is flat and properly aligned with the enclosure frame.
• Ensure that all grounding and bonding connections are secure and meet local electrical codes .

Maintenance Tips

Before performing maintenance, cut off power, clean dust, and inspect busbars and joints for discoloration, rust, or overheating . Proper welding and assembly of the back panel directly impact the safety and longevity of the distribution box. By following these guidelines, the back panel will provide mechanical strength, electrical safety, and environmental protection for the distribution box.