Copper Bar, also known as copper bus bar or copper bus bar, is made of copper material, long Rectangular or chamfered rectangular conductors (now generally copper fillets to avoid tip discharge) that act as current carriers and electrical connections in a circuit.

Copper bars are widely used in electrical equipment, especially in complete sets of distribution equipment. The U, V, W phase busbars and PE busbars in distribution cabinets are usually copper bars Copper row in use generally marked with the color letters or painted with color paint, U phase copper row painted with "yellow" color, v phase copper row painted with "green" color, W phase copper row painted with "red" color, PE bus bar copper row painted with "yellow and green" two-color. Today we are going to learn about the relevant calculation of Copper Bar!

1.Calculation of current carrying capacity of copper bar

First of all, we should understand the installation of copper row in the cabinet in two forms, horizontal and vertical, vertical load slightly larger than horizontal, so the main bus distribution cabinet is mostly vertical form. There are copper, copper wire carrying capacity will also change with the change in ambient temperature, here we are the most is the ambient temperature of 35 degrees Celsius. At different ambient temperatures, the current carrying capacity is multiplied by the correction factor at different ambient temperatures, and the higher the temperature, the lower the current carrying capacity.

Based on experience, the following conclusions are drawn: Single Copper Busbar carrying capacity = width (mm) x thickness factor; double busbar carrying capacity = width (mm) * Thickness Factor * 1.5(Empirical Factor) ; Copper Busbar and Aluminum Busbar can also be squared, usually copper at 5-8 a/squared, aluminum at 3-5 a squared. The current-carrying capacity of common copper bars is calculated as follows: At 40 °C, the current-carrying capacity of copper bars = row width * Thickness Coefficient (thickness + 8) ; row width (mm) ; thickness Coefficient is 20 when the Busbar is 12 thick; 18 when the Busbar is 10 thick; the order is [12-20,10-18,8-16,6-14,5-13,4-12] . Double-layer Copper Bar [40 °C ] = (1.56-1.58) * single-layer Copper Bar [40 °c ](depending on the size of the Cross section) ; three-layer Copper Bar [40 °c ] = 2 * single-layer Copper Bar; four-layer Copper Bar [40 °c ] = single-layer Copper Bar [40 °c ] * 2.45.

For example, for TMY100 * 10 the carrying capacity is: Single Layer: 100 * 188 = 1800(a)[ search manual for 1860A ] ; Double Layer: 2(TMY100 * 10) the carrying capacity is: 1860 * 1.58 = 2940(a) ; [ search manual for 2942A ] ; Three: 3(TMY100 * 10) carrying capacity: 1860 * 2 = 3720(a)[ search manual for 3780A ] above all calculations are accurate to the manual data very close.

2.Calculation method of copper bar bending

01. Outside Algorithm of Flat Bend (Right Angle Bend)

MATERIAL LENGTH: total length = a + (material thickness) + b + (material thickness) + C + d-coefficient * Number of Right Angle Bends Note: material length is based on the addition factor as follows:

02. Horizontal (Right Angle) inner algorithm

03. For example, when the material thickness is 3mm, the total length = l + 0.3 + H + 0.3 when the material thickness is 10mm, the total length = l + 1.5 + H + 1.5 Note: Each angle is added twice

3.Selection of copper bar in high-pressure cabinet

The selection of copper bar section of high-voltage cabinet must meet two requirements: 

(1) meet the rated current 

(2) meet the short-term withstand current, so the second one needs to write down the formula in GB3906[ Appendix D ] : s = I/a √(T/△) formula: I rated short-time withstand current; a -- Quality Coefficient, copper = 13, aluminum = 8.5; T —— Rated short-circuit duration; △ -- Temperature Rise (K) , the average bare conductor is 180K and the 4S duration is 215K. Then: The minimum cross-sectional Area S = (25/13) * √4/215 = 260mm2 for a 25KA/4s system; the minimum cross-sectional Area S = (31.5/13) * √4/215 = 330mm2 for a 31.5 ka/4s system; the minimum cross-sectional Area S = (40/13) * √4/215 = 420mm2 for a 40KA/4s system; S = (63/13) * √4/215 = 660 MM2; s = (80/13) * √4/215 = 840 MM2 for 80 ka/4s; the calculated copper Bar cross-section should be selected by the maximum. For example, the current parameters given by the Design Institute in a circuit are: rated current 630A, short-term withstand current 31.5 Ka, tMY-40 * 6 should be used for the calculation of the rated current 630A and TMY-60 * 6 for the calculation of the short-term withstand current of 31.5 Ka (the minimum cross-sectional area of the 31.5 ka/4s copper bus is 330mm2) , the Cross section of TMY-60 * 6 is 360mm2, which is larger than the minimum cross section of 330mm2 in the above table. According to the maximum of two conditions: rated current 630A, short-term withstand current of 31.5 Ka bus should choose TMY-60 * 6.

 Source: The Web