what is the strandard bending for a busbar?Busbar trunking itself doesn’t have a single, fixed “standard bend” or “bend radius” like pipes. Its bending capacity depends entirely on its design and manufacturing standards.

Simply put, different types of busbar trunking have completely different bend radii or angles. We can’t simply say, “All busbar trunking has a bend radius of XX meters.”

Below, I’ll explain this in detail and provide the key information and reference standards you need.

Core Determinant: Busbar Trunk Type

Busbar trunking falls into two main categories, each with distinctly different “bend” methods:

1. Rigid Busbar Trunk

This type of busbar trunking is inherently straight and unbendable. Bends are achieved through standardized elbow assemblies.

· Standard Angle: This type of busbar trunking has standard elbow angles, the most common of which are:
· 90° horizontal elbow: changes horizontal direction.
· 90° vertical elbow: connects horizontal busbars to vertical busbars (e.g., between floors). · 45° elbows, 30° elbows, etc.: Used to achieve non-right-angle turns, allowing for more flexible routing.
· T- or X-shaped elbows: Used for branch connections.
· Conclusion: For rigid busduct, there’s no concept of “bendability”; only standardized elbow components. You need to select elbows with the appropriate angle and specifications based on the design drawings.

2. Flexible busduct

This type of busduct is truly “bendable.” It’s typically used to bypass obstacles during installation, absorb structural movement, or reduce vibration transmission. Its bending capacity is a key parameter.

· Key Parameter: Minimum Bend Radius
· This is the most important specification for flexible busduct. It means that when bent, the inner bend radius of the busduct must not be less than the minimum value specified by the manufacturer.
· This value is usually clearly stated in the manufacturer’s technical manual, such as “Minimum Bend Radius = 2 x W” (W is the busduct width), or as a specific value such as R600mm or R1000mm. Factors Affecting the Minimum Bend Radius:

Conductor Structure: Conductor cross-sectional area, number of conductors, and stacking method.

Insulation Material: The flexibility of the insulation layer.

Casing Material: Bellows-type casings offer the best flexibility.

Current Rating: Generally, the higher the current, the thicker and stiffer the conductor, and the larger the minimum bend radius.

Related Standards and Specifications

While there is no standardized value for “bendability,” the design, manufacture, and testing of busbar trunking must adhere to strict national and international standards. These standards ensure the electrical and safety performance of elbow assemblies or flexible units.

International Standards:

IEC 61439-6: “Low-voltage switchgear and controlgear assemblies — Part 6: Busbar trunking systems (busbar trunking).” This is currently the most authoritative standard globally.

Chinese National Standards:

GB 7251.6: “Low-voltage switchgear and controlgear assemblies — Part 6: Busbar trunking systems (busbar trunking).” This standard is equivalent to IEC 61439-6.

What do these standards specify?

They do not specify specific bend radii, but rather specify type tests that busbar trunking systems (including all straight sections and elbows) must undergo to ensure:

· Temperature rise limit: At rated current, the temperature at joints such as elbows must not exceed safety limits.

· Short-circuit strength: The system can withstand short-circuit current surges for a specified duration.

· Protection level: Bends must meet the same protection level as straight sections, such as IP54 or IP66.

· Clearance and creepage distances: Safety requirements must also be met at bends or joints.

Summary and Practical Advice

1. There is no universal “standard bend”: The bending capacity of busbar trunking varies depending on the type and specific product.
2. For rigid busbar trunking, standard elbows (90°, 45°, etc.) are used, eliminating the need to calculate bend radii. Please consult the manufacturer’s product datasheet to select the model. 3. Flexible busduct: The key parameter is the “minimum bend radius.” This value must strictly adhere to the manufacturer’s technical data sheet and must not be less than this value during installation. Failure to do so will severely damage the insulation and conductors, leading to failure.
3. Design Basis: During electrical design, the required elbow type and angle (for rigid busduct) should be determined based on the building structure and equipment layout, or sufficient bending space should be reserved (for flexible busduct).
4. Final Authority: In all cases, the most accurate and authoritative source of information is the “Product Technical Manual” or “Installation Instructions” for your selected busduct brand. Be sure to obtain and carefully review these instructions from the supplier before purchasing and installation.

Busbar manufacturing requires a busbar processing machine, so choosing the right one is crucial. The following copper busbar processing machine recommendations may be helpful: