1. Scope
This document specifies the methods and requirements for manufacturing and assembling busbars.
This document is applicable to the manufacture and assembly of busbars for high and low voltage switchboards, prefabricated high/low voltage substations, distribution boxes and other complete equipment.
2. Referenced Patterns
GB/T 17467-1998 Prefabricated high/low voltage substations
GB/T 11022-1999 Common Technical Requirements for High Voltage Switching and Control Equipment
GB 7251.1~4 Complete low voltage switchgear and control equipment
Electrical installation engineering GBJ149-90
Specifications for construction and acceptance of bus devices
Copper busbar” International Copper Association (China)
Compilation of electrical regulations of the Electric Power Industry Association in the Beijing area
GB 5585.1-2005 Busbars for Electrical Purposes Part 1: General Provisions
GB 5585.2-2005 Busbars for Electrical Purposes Part 2: Copper Busbars
GB2681-81 Wire Colors in Complete Fixtures
3. Materials
Copper busbars (rectangular, I-shaped, D-shaped, double-T-shaped, triple-T-shaped, etc.), aluminum busbars, insulators, heat shrink tubes, galvanized screws, nuts, flat washers, washers pressure gauge, grease conductive electrical contact, (yellow, green, red), (L1, L2, L3) and various phase labels.
4. Equipment and Tools
Busbar straightening machine, busbar cutting machine, busbar bending machine, polishing machine, drilling machine, vertical drill, electric furnace, tin pan, hacksaw, file, screwdriver, hand hammer, wooden hammer, tape metric, steel ruler, square, scribing needle, wire brush wheel, scissors, spray gun, wrench, torque wrench, etc.
5. Busbar Manufacturing Principles
5.1 The bus specification is selected according to the technical requirements of the project.
The bus routing scheme is generally determined by the manufacturer, but must consider the installation position of components and actual installation conditions.
On the premise of meeting relevant technical requirements, it must adhere to the principles of reasonable layout, material saving, cleanliness and aesthetics.
The installation must be safe, reliable and easy to maintain and dismantle. The wiring of the same contracted product must be as uniform as possible.
5.2 This document requires that the primary circuit generally uses copper bars. In special cases, with the authorization of the head of the technical department or the chief engineer, insulated wires may also be used. For continuous currents above 100A, copper bars must be used.
5.3 The specification of the primary line is determined according to the user's design requirements, but should not be lower than this regulation. When the design does not specify the specification, the corresponding specification must be found according to the wire capacity. See “Wire Current Carrying Capacity Table” in this process guideline.
a) For selection of current carrying capacity of TMY copper busbar, see Appendix A.
b) For the current carrying capacity of BVR and BV PVC insulated wire, see Appendix B.
5.4 On the premise of meeting the above requirements, the number of bus bends must be minimized to avoid bus crossing.
6. Bus processing technology
6.1 Bus processing usually includes the following technological processes:
a) Select the bus specification according to the technical requirements of the project, determine the wiring scheme and measure the manufacturing dimensions of the bus;
b) Straighten the copper busbar with a busbar straightener;
c) Cut according to the unfolded dimensions, the cross section must be flat and without burrs;
d) Make or drill holes, deburr the marked holes;
e) Bending flat, vertical and torsional curves according to the plan; (The surface of the busbar must be clean and flat, without cracks, wrinkles, impurities and deformations and twists.)
f) Carry out an antioxidant treatment on the overlapping surface of the busbars (tin-plated or silver-plated).
6.2 After cutting the busbar, it must be straightened and the cut surface smoothed with a file.
6.3 The burrs after drilling or punching the busbar must be machined flat, and the surface of the busbar must not have obvious hammer marks, scratches, holes, peeling and other defects.
6.4 Between double or multiple rectangular busbars, a gap not less than the thickness of the busbar must be maintained; the distance between the edges of adjacent spacers must be more than 5 mm.
6.5 The same layout of main bus, branch bus, overhead line and equipment connecting line should be symmetrical, horizontal and vertical, clean and beautiful.
6.6 The arrangement of the bus phase sequence, when the project does not specify, must comply with the following standards:
a) For AC buses arranged up and down, the top to bottom arrangement is phase A, B, C, N, the positive pole of the DC bus is up, the negative pole is down.
b) For horizontally arranged AC buses, the arrangement from the back of the tray to the surface of the tray is phase A, B, C, N, the positive pole of the DC bus is at the back, the negative pole is at the front.
c) For left to right pendant wire AC bus, the arrangement is phase A, B, C, N, DC bus positive pole is on the left, negative pole is on the right.
Note: The arrangement of the phase sequence is based on the direction of the front view of each substation room. In special cases, when the arrangement in this sequence of phases will definitely cause difficulties in positioning the busbars, it is not necessary to follow this regulation, but each phase must have a clear indication.
6.7 Bus Bending
6.7.1 Rectangular busbars must be cold bent, hot bending is not permitted.
6.7.2 The bending of busbars must comply with the following standards (Figure below):
a) Rectangular buses must minimize right-angled bends and the bending angle must not be less than 90 degrees. There must be no significant cracks or wrinkles in the bend, and the minimum bending radius of the busbar must be in accordance with regulations, see the figure below.
b) The distance from the point where the busbar begins to bend to the edge of the nearest insulator busbar support clamp shall not exceed 0.25L but shall not be less than 50mm.
c) The distance from the point where the busbar starts to bend to the busbar connection location should not be less than 50 mm.
Table 6.7.2: Minimum value of the bending radius (r) for busbars
| Bus type | Types of curves | Bus cross section size (mm) | Minimum bending radius (mm) | ||
| Copper | Aluminum | Steel | |||
| Rectangular Bus | Flat curve | 50×5 and below | 2a | 2a | 2a |
| 125×10 and below | 2a | 2.5a | 2a | ||
| Vertical Curve | 50×5 and below | 1b | 1.5b | 0.5b | |
| 125×10 and below | 1.5b | 2b | 1b | ||
| Rod-shaped bus | Φ16 and below | 50mm | 70mm | 50mm | |
| Φ30 and below | 100mm | 150mm | 150mm | ||
Note: 'a' is the busbar thickness and 'b' is the busbar width.
d) When the busbar is rotated 90°, the length of the rotated part must be 2.5 to 5 times the width of the busbar (Figure 6.7.2.2).
e) The bending of various busbars must be consistent.
6.8 Connections to rectangular busbars must be made by welding, screws or clamps. Cylindrical busbars must be connected using welding or wire clamps. Bus connections must meet the following requirements:
6.8.1 When rectangular busbars are overlapped with screw fixation, the distance from the connection to the edge of the insulator support plate must not be less than 50mm. The distance from the upper end of the busbar to the place where the lower busbar begins to bend must not be less than 50mm (Figure 6.8.1). (Note: If conditions permit, the two busbars can be overlapped directly without bending, but it must be ensured that the busbars are not subject to external stresses.)
6.8.2 Overlapping methods for rectangular busbars: When busbars are connected to equipment terminals, they must meet the requirements of the national standard “Connection terminals for transformers, high voltage devices and bushings”. If necessary, double or multiple bus transition connections must be used. When there are no special requirements, they must comply with the standards set out in the following table:
| Vertical Overlay | Serial number | Connection dimensions (mm) | Hole diameter Φ | Screw Specification | ||
| b2 | b1 | The | ||||
 |
1 | 15 | <2 b2 | 7 | M6 | |
| two | 20 | 11 | M10 | |||
| 3 | 25 | 11 | M10 | |||
| 4 | 30 | 13 | M12 | |||
 |
5 | 15 | ≥2b2 and ≤3b2 | 7 | M6 | |
| 6 | 20 | 11 | M10 | |||
| 7 | 25 | 11 | M10 | |||
| 8 | 30 | 13 | M16 | |||
 |
9 | 15 | ≥3b2 | 40 | 7 | M6 |
| 10 | 20 | 40 | 11 | M10 | ||
| 11 | 25 | 50 | 11 | M10 | ||
| 12 | 30 | 60 | 13 | M16 | ||
 |
13 | 40 | ≥40 | 11 | M10 | |
| 14 | 50 | ≥50 | 13 | M12 | ||
 |
15 | 60 | ≥60 | 11 | M10 | |
| 16 | 80 | ≥80 | 17 | M16 | ||
| 17 | 100 | ≥100 | 17 | M16 | ||
| 18 | 120 | ≥120 | 17 | M16 | ||
 |
1 | 15 | 15 | 30 | 7 | M6 |
| two | 20 | 20 | 40 | 11 | M10 | |
| 3 | 25 | 25 | 50 | 11 | M10 | |
| 4 | 30 | 30 | 60 | 13 | M12 | |
 |
5 | 40 | 40 | 80 | 11 | M10 |
| 6 | 50 | 50 | 80 | 13 | M12 | |
 |
7 | 60 | 60 | 60 | 11 | M10 |
| 8 | 80 | 80 | 80 | 17 | M16 | |
| 9 | 100 | 100 | 100 | 17 | M16 | |
| 10 | 120 | 120 | 120 | 17 | M16 | |
6.8.3 The diameter of the bus joint screw hole must be greater than the screw diameter by 1mm; Drilling should be vertical, not distorted, and the error in the center distance between screw holes should be ±0.5 mm.
6.8.4 The bus contact surface must be flat and free from oxide films (polished with a steel brush wheel). After processing, the reduction of its cross-section: the copper busbar must not exceed 3% of the original cross-section; the aluminum busbar must not exceed 5% of the original cross section.
6.8.5 For overlapping surfaces of busbars with a silver layer, arbitrary filling is not allowed. For non-darkening silver-plated contact surfaces, simply clean with anhydrous alcohol or acetone or gasoline until it runs out. If the silver layer turns black, it can be lightly polished with metallographic sandpaper and then cleaned with anhydrous alcohol.
6.8.6 Installation of busbar and busbar or busbar and electrical terminal screw overlapping surfaces must meet the following requirements:
a) The bus contact surface must be kept clean after processing.
b) When the busbar is placed flat, the through bolt must be threaded from bottom to top, in other cases the nut must be on the maintenance side and the length of the bolt must protrude from the nut by 2 to 5 threads.
c) There must be flat washers on both outer parts of the busbar connected by the through bolt, there must be more than 3mm net distance between the washers of adjacent bolts, and there must be a lock washer or lock nut on the nut side.
d) The screws must be uniformly tensioned and must not subject the electrical terminal to extra tension.
e) The bus contact surface must be well connected, the connection screws must be tightened with a torque wrench and the tightening torque value must comply with the provisions of Table 6.8.6:
Table 6.8.6 Steel Screw Tightening Torque Value
| Screw Specification (mm) | Torque Value (N·m) |
| M8 | 8.8~10.8 |
| M10 | 17.7~22.6 |
| M12 | 31.4~39.2 |
| M14 | 51.0~60.8 |
| M16 | 78.5~98.1 |
| M18 | 98.0~127.4 |
| M20 | 156.9~196.2 |
| M24 | 274.6~343.2 |
f) When the busbar is connected to the screw terminal, the opening of the busbar should not exceed the diameter of the screw terminal by 1 mm. The oxide film on the line must be cleaned with a brush. The nut contact surface must be flat. A tinned copper flat washer must be added between the nut and busbar, and a locknut must be provided, but no lockwasher must be added.
g) After installing the busbar, there must be no internal tension and there must be no significant sagging. Deviation within two support points should not exceed 4mm. All contact parts of the bus joints must be closely matched. After tightening the screws, a 0.05mm feeler gauge should be used for inspection. The depth of the feeler gauge shall not exceed 6mm for busbars with a width greater than 60mm, and shall not exceed 4mm for busbars with a width less than 60mm.
6.8.7 The busbar must meet the following requirements when fixed to the pillar insulator:
6.8.7.1 The fixing of the busbar and the pillar insulator must be flat and firm, not subjecting the supported busbar to extra efforts. When the length of the bus exceeds that predicted in Table 6.8.7.1, a fixed support must be added in the middle.
Table 6.8.7.1 Intervals for adding fixed support to busbars (mm).
| Bus width | Distance | Bus width | Distance | Bus width | Distance |
| ≤30 | 300 | ≤50 | 600 | ≥60 | 900 |
6.8.7.2 Fixing accessories or other AC bus support accessories must not form a closed magnetic circuit.
6.8.7.3 When the busbar is laid flat, the upper pressure plate of the busbar support clamp should maintain a gap of 1mm ~ 1.5mm with the busbar. When the busbar is assembled, the upper pressure plate should maintain a gap of 1.5mm ~ 2mm with the busbar.
6.8.7.4 For each section of the busbar fixed to the pillar insulator, a dead point must be defined, preferably at the midpoint of the entire length or between the two expansion joints of the busbar.
6.8.7.5 All parts of the busbar fixing device with edges and corners must be blunt to prevent tip discharge.
6.9 Selection of neutral axis cross section N
6.9.1 In a three-phase four-wire power supply system, the cross-section of the neutral line N must be the same as that of the phase line.
6.9.2 The cross-sectional area of the PEN conductor must be determined in the same way as the neutral conductor N. However, the minimum cross-sectional area must not be less than 10 mm2. The cross-section of the protective conductor is selected according to Table 6.9.2.
Table 6.9.2 Reference table for selecting the cross-sectional area of the protective conductor (mm 2 ).
| Cross-sectional area S of the device's phase conductor. | Minimum Cross-Section Area of Sp Protective Conductor |
| S≤16 | s |
| 16＜S≤35 | 16 |
| 35＜S≤400 | S/2 |
| 400＜S≤800 | 200 |
| S>800 | S/4 |
6.10 After creating the busbar, it must be isolated and protected by heat-shrinkable tube. The specific requirements are as follows:
6.10.1 Cutting: Select a heat shrink tube that matches the cross section of the busbar. Cut the pipe so that its length matches the length of the bus and there should be no oblique mouth. There should be no joints in between. (Tube length decreases about 3% to 5%)
6.10.2 Insertion: Insert the bus. If insertion is difficult, you can spray lubricants such as silicone oil on the busbar to prevent creases and make insertion easier.
6.10.3 Start shrinking: Use medium heat to shrink. For Z-shaped busbars, start shrinking from the middle of the busbar. At the same time, keep the flame moving to prevent the tube from burning.
6.10.4 Shrinkage of the right-angle part: When the right-angle part shrinks, squeeze the tube to avoid creases caused by small fires.
6.10.5 Shrinking the second piece at right angles: In the same way, tighten the tube and keep the flame moving.
6.10.6 Shrinking the Straight Part: Keep the flame moving and use medium heat for even heating.
6.10.7 Bubble problem: If bubbles appear in the tube, heat it thoroughly over medium heat until the bubbles disappear.
6.10.8 Correction: If there are wrinkles or excessive stretch on the tube surface, correct before cooling to fit the busbar.
6.10.9 Cooling: Cool the busbar to complete the shrinking process.
6.10.10 After thermal contraction, the busbar must be checked for flatness, burns, breaks and scratches, and must be carefully coded.
6.11 The overlapping surface of the busbar and the heat shrinkable position of the heat shrinkable tube are shown in the figure:
6.12 Rectangular busbars must avoid the arch area. When the main AC circuit passes through a metallic structure forming a closed magnetic circuit, the three-phase buses must pass through the same hole in the structure. When connecting the secondary line to the primary bus, it is necessary to separately drill holes in the bus and fix it with screws.
6.13 Device insulator wires are generally black unless the user has special requirements. The ground wire is yellow and green. The ends of the wires are distinguished by different colors of insulated ends or plastic sleeves of different colors. Copper and aluminum busbars are labeled with colored labels to identify the phase sequence.
The. AC Circuit: Phase A – Yellow, Phase B – Green, Phase C – Red, Neutral – Light Blue, Ground – Yellow and Green.
B. DC Circuit: Positive – Brown, Negative – Blue.
6.14 Bus overlaps must not be spray painted; Colored adhesive labels can be used in visible positions on the bus observation surface.
6.15 The color and phase sequence of the buses are shown in Appendix C.
6.16 Requirements for busbar insulation clearance must meet the following requirements:
6.16.1 The electrical clearance on the low voltage side shall not be less than 20 mm.
6.16.2 The distance between the bare energized bodies of the different phases on the high voltage side and between the bare energized parts and the grounded skeleton shall not be less than 125mm; the distance between live parts and the front metal cover plate, metal door or transmission rod should not be less than 155 mm; the distance between the bare live parts and the front network cover plate or network port should not be less than 225 mm.
6.16.3 After the bus is installed, it must meet the design standards, the connections must be correct, the screws must be tight, the contact must be reliable, the phase color marking must be visible, not easy to fall off, and the ending must be clean and attractive.
Note: The above dimensions cannot be used as a basis for electrical insulation resistance. The electrical gap of the electrical components themselves is not subject to the above size restrictions.
7. Precautions
7.1 Pay attention to personal safety during busbar production to avoid shocks, scratches and burns;
7.2 The manufactured busbar must not be climbed, stepped on or pulled;
7.3 The busbar material used must be stacked neatly to avoid dirt and deformation;
7.4 Pay attention to workplace hygiene.
8. Related documents for reference
2904-1 General technical rules for wiring auxiliary circuits
2905-1 Technical standards for processing and fixing marking plates and symbols.
Appendix A
(Suggestive Appendix)
TMY bus current carrying capacity table
| Rated current (A) | Copper busbar specifications (single piece in mm) |
| Below 185 | 16×1.6、15×3、10×4 |
| 242 | 20×3 |
| 300 | 25×3、16×5 |
| 355 | 30×3、20×4 |
| 420 | 30×4、20×6 |
| 550 | 40×4、30×5、20×10 |
| 615 | 50×3、40×5、30×6、25×8 |
| 755 | 60×3、50×5、40×6、30×10 |
| 840 | 60×4、50×6、40×8、25×16 |
| 900 | 80×3、60×5 |
| 990 | 60×6、50×8、40×10、30×16 |
| 1160 | 80×4、60×8、50×10、40×16 |
| 1300 | 100×4、80×6、60×10、50×12 |
| 1490 | 100×5、80×8、60×12、50×16 |
| 1590 | 100×6 |
| 1670 | 80×10、60×16 |
| 1830 | 120×6、100×8、80×12 |
| 2030 | 100×10 |
| 2110 | 120×8、100×12、80×16 |
| 2330 | 160×6、120×10、100×16 |
| Rated current (A) | Copper busbar specifications (double piece in mm) |
| 1530 | 60×6 |
| 2300 | 80×8 |
| 2730 | 80×10 |
| 2690 | 100×8 |
| 3180 | 100×10 |
| 3610 | 120×10 |
Note: The ambient temperature is 35°C and the maximum working temperature is 70°C.
Appendix B
(Informative Appendix)
Current Carrying Capacity of PVC Insulated Copper Core Wires BVR, BV
| Wire cross section (mm 2 ) | Wire Laying (A) |
| 1 | 6 |
| 1.5 | 8 |
| 2.5 | 12 |
| 4 | 16 |
| 4 | 25 |
| 6 | 32 |
| 10 | 40 |
| 10 | 63 |
| 16 | 80 |
| 25 | 100 |
| 35 | 125 |
| 50 | 160 |
| 70 | 200 |
| 95 | 250 |
| 120 | 300 |
| 150 | 315 |
| 185 | 400 |
Note: Current carrying capacity is the empirical value of current when the ambient temperature is 35°C and the wire is exposed. Select according to technical requirements in special cases.
Appendix C
(Suggestive Appendix)
Bus color and phase sequence (installation location is according to the front view of the screen/cabinet)
| Group | Bus installation positions relative to each other | ||||
| Color | Horizontal arrangement | Front and rear arrangement | Vertical arrangement. | ||
| Alternating current | Phase A | Yellow | Left | Distant | Main |
| Phase B | Green | Quite | Average | Quite | |
| Phase C | Red | Right | Zoom in | Bottom | |
| Neutral Line | Light blue | More to the right | Closer | Lower | |
| PE Line | Yellow-Green Alternation | More to the right | Closer | Lower | |
| Direct current | Positive | Brown | Left | Distant | Main |
| Negative | Blue | Right | Zoom in | Bottom | |
| Neutral Line | Light blue | – | – | – | |
