Selection guide for standard copper bars

1. purpose
Standardize the size selection of copper bars used in switchgear cabinets, that is, select the appropriate cross-sectional specifications in the design of copper bars to ensure the rated current capacity of copper bars in the corresponding use environment.

2. Scope of application
Copper and copper alloy busbars for all electricians.

3. Selection guide for copper bars in low-voltage switchgear
3.1 Normal use conditions of copper bars in low-voltage switchgear cabinets
Copper bar material: TMY and THMY in accordance with GB/T5585.1-2005 standard;
Conditions of use: ambient temperature 35 ℃, allow temperature rise 70K;
Altitude: <1000m;
Rated working frequency: 50/60Hz.
If the conditions of use are inconsistent with the above, according to the specific conditions of use of copper bars, the current carrying capacity of the copper bars shall be re-checked according to Article 4 of this guide.

3.2 System level main bus selection
Under normal use conditions, the technical support engineer selects or modifies the specifications of the horizontal main bus according to the rated current of the low-voltage system according to Table 1. If the design institute does not agree to the modification, the technical support engineer must work with the mechanical design engineer to confirm the specification selection of the horizontal main bus.
Table 1: Rated current-carrying table of horizontal bare copper busbars (copper bars are placed vertically, with a single-phase a=110, double a=110, and three a=130).