I. Subject Content and Applicable Scope
These guidelines apply to the processing and busbar installation of all low-voltage distribution boards and power distribution boxes produced by our factory. In addition to electrical clearance and creepage distance, other principles can also be used for high voltage enclosures.
II. Bus Selection
Busbars should be selected based on circuit current, long-term allowable temperature rise conditions, and dynamic thermal stability requirements. They must be aluminum or copper busbars and plastic wires with a copper core.
The selected busbars must comply with standards GB5584-85 “Aluminum Busbar” and GB55852-85 “Copper Busbar”. One must also consider the impact of heat dissipation conditions on load capacity when placed vertically (good) versus placed horizontally (bad).
If the user has other requirements, the appropriate bus must be selected in accordance with these requirements.
1. Common busbar specifications and current carrying capacity are shown in Appendix A1
2. Copper core plastic wires are shown in Appendix A2
III. Materials, equipment and tools
1. Various specifications of copper and aluminum screws, nuts, washers and gaskets
2. Bent line cutting machine, punching machine, drill and drills, manual press brake, bench vise, socket wrench, strap wrench, wrench, file, scriber, steel tape measure, square ruler, steel ruler, knife electrician's tool, screwdriver, wire pliers, hand drill, etc.
4. Processing steps and technical requirements
1. Before processing the busbar material, it must undergo external inspection. If cracks, stains, holes or various deposits are found on the surface, or if there are large pores on the surface (diameter of aluminum busbar greater than 5 mm, depth greater than 0.55 mm, diameter of copper busbar greater than 5 mm, depth greater than 0.15 mm), this section must be cut.
2. All busbar must be basically straight before cutting. If there is obvious irregularity or straightness, it must be corrected.
3. Cut according to the drawing or model size (for example, cutting on the cutting machine or punching machine) and remove burrs during processing.
After cutting, if it is found to be uneven, not straight or twisted, it must be corrected with a wooden hammer or similar tool. After correction, there should be no obvious hammer marks on the busbar.
4. Bend the busbar according to your own requirements or specific distribution cabinet requirements. When the busbar is bent, care must be taken not to use too much force or speed to avoid cracking. The degree of bending of the two parallel buses of the same phase must be consistent.
(1) The minimum allowable radius for busbar bending is shown in Appendix A3.
(2) Cracks are not allowed after the busbar is bent.
(3) The bending points of the same group of busbars must be basically consistent after installation.
5. Bus Hole Drilling
(1) The pairing of busbar hole and screw specifications is selected in accordance with Appendix A4.
(2) After determining the hole size according to the specifications of the bus used, overlap shape and electrical pile head shape, drill holes on a drill or punching machine.
(3) After processing the busbar, the cuts and edges of the holes must be deburred and chamfered.
6. Both the connection points between busbars and between busbars and electrical pile heads must be tinned and driven, applying neutral petroleum jelly to the tinned connection parts. Depending on the technical conditions of the plant, conductive paste may be used instead of tinning.
(1) For detailed busbar tinning procedures, see the “Tinning Process Guidelines”. For conductive paste application, see “Conductive Paste Application Guidelines”.
(2) Crimping of the busbar must be done using a dedicated crimping die on a punching machine.
(3) Before crimping, the crimping limit must be marked (generally 20mm from the connection edge).
7. All busbars must be painted black. Painted edges should be basically in one line, with no missing paint, drip marks, foreign objects or other traces. The overlapping surface should not be painted and the distance between the painted edge and the overlapping edge should be between 5-10mm.
V. Busbar with plastic wires with copper core
Busbars with a current rating of less than 200A can be replaced with copper-core plastic wires, with copper/aluminum connectors crimped at both ends.
Stripping length and selected connectors are shown in Appendix A5. The exposed part of the crimping area must be wrapped with electrical tape.
SAW. Bus installation
1. Before installing the bus, inspect the quality of the bus and its accessories. Unqualified items cannot be installed.
2. When the busbar is long (generally low voltage enclosure >0.8M, GCK >0.4M), a suitable busbar clamp and insulator should be used for fixing in the middle.
3. When the main bus overlaps, the three phases must be staggered layer by layer and not crossed. When two or more buses are used in parallel for the same phase, there must be a thickness of space between the two (to increase the heat dissipation area).
4. During installation, the overlapping surfaces from busbar to busbar and busbar to electrical pile head must be naturally flat. No external force should be used to press it, causing stress on the bus, affecting the switch components and the dynamic thermal stability of the bus.
5. After tightening the screws, there must be sufficient contact pressure between the overlapping surfaces. The tightness of the contact can be checked with a 0.05x10mm feeler gauge.
For busbars wider than 63 mm, the insertion depth in any direction must not exceed 6 mm. For those under 56mm, the insertion depth should not exceed 4mm. The screw head must protrude 2 to 5 threads from the nut (after tightening). It should not be too short nor too long.
6. When the busbar is flat, the screw must be inserted from top to bottom. When vertical, it must be inserted from front to back, that is, the nut must be placed behind.
7. If there are difficulties in the contact area or layout, a transition bar connection can be added as needed.
8. The main busbar must be securely secured with a busbar clamp.
9. Except in special circumstances, buses shall be installed in accordance with drawing requirements. Its layout and installation must guarantee electrical clearance (≥12mm) and creepage distance (≥14mm) between the busbar and other components and elements, auxiliary parts.
The minimum electrical clearance and creepage distance requirements also meet the values specified in Table A8. It also meets the arc spray distance requirements (see “Electrical component, auxiliary installation, adjustment process rules”).
10. For all horizontal busbars, vertical busbars, branch busbars and live parts between main circuit connectors in drawer cabinets, and their electrical clearance and creepage distance from grounded metal parts, the rated voltage shall be between 380V-660V and should not be less than 20mm.
Insulation wrap, insulation sleeve, epoxy powder spraying or other insulation materials may be used as the busbar insulating layer to reduce the busbar clearance requirements, but must still meet the provisions of Table A8.
11. For other forms of low voltage switches, the electrical clearance and creepage distance between the main circuit busbars shall also refer to the provisions of Article 10 when the dynamic thermal stability current passes and may cause a reduction in clearance electrical.
12. See Appendix A6 for typical connection ways and bus overlap requirements.
VII. Apply sequence markers
After bus installation, phase sequence signs must be posted in a prominent position on the bus, or three-color paint blocks must be painted to indicate the phase sequence (Phase A: yellow; Phase B: green; Phase C: red).
(1) See Appendix A7 for the bus phase sequence arrangement in the cabinet.
VIII. Quality inspection
(1) Check whether there are cracks on the bus bend and whether the surface is smooth.
(2) Check whether the tinning location of the busbar is smooth, shiny and uniform, and use a feeler gauge to check whether the gap between the overlapping surfaces of the busbar meets the requirements.
(3) Check whether the busbar is firmly installed and overlapped, whether the layout is beautiful, and whether it meets the requirements of electrical clearance, creepage distance and arc spraying distance.
(4) Whether the phase sequence mark is correct.
Appendix A1 Single Rectangular Busbar Specifications and Current Carrying Capacity.
| TMY Copper Busbar | |||||
| Bus cross section（ ㎜2 ） | Maximum allowable current (A) | ||||
| Horizontal Placement | Vertical Placement | ||||
| Specification | Area | 25℃ | 40°C | 25℃ | 40°C |
| 15×3 | 45 | 200 | 167 | 210 | 171 |
| 20×3 | 60 | 261 | 212 | 275 | 224 |
| 25×3 | 75 | 323 | 263 | 340 | 277 |
| 30×4 | 120 | 451 | 368 | 475 | 387 |
| 40×4 | 160 | 593 | 483 | 625 | 509 |
| 40×5 | 200 | 665 | 541 | 700 | 570 |
| 50×5 | 250 | 816 | 665 | 860 | 700 |
| 50×6 | 300 | 905 | 738 | 955 | 778 |
| 60×6 | 360 | 1069 | 893 | 1125 | 916 |
| 60×8 | 480 | 1251 | 1019 | 1320 | 1075 |
| 60×10 | 600 | 1395 | 1136 | 1475 | 1202 |
| 80×6 | 480 | 1360 | 1108 | 1480 | 1206 |
| 80×8 | 640 | 553 | 1265 | 1690 | 1377 |
| 80×10 | 800 | 17847 | 1423 | 1900 | 1548 |
| 100×6 | 600 | 1665 | 1356 | 1810 | 1475 |
| 100×8 | 800 | 1911 | 1557 | 2080 | 1695 |
| 100×10 | 1000 | 2121 | 1728 | 2310 | 1882 |
| 120×8 | 960 | 2210 | 1810 | 2400 | 1956 |
| 120×10 | 1200 | 2435 | 1984 | 2650 | 2159 |
Appendix A3: Minimum radius (R) for busbar bending (flat curve) (busbar thickness b)
| MATERIAL/Specifications | TML | LMY |
| ≤5×50 | R=2b | R=2b |
| >5×50 | R=2b | R=2.5b |
Appendix A4: Busbar, screw hole and diameter adjustment
| Screw diameter | Bus hole | Screw diameter | Bus hole diameter |
| M6 | ￠6.5 | M12 | ￠13 |
| M8 | ￠9 | M16 | ￠18 |
| M10 | ￠11 |
Appendix A5
| Terminals (mm) | Wire stripping length (mm) |
| 10 | 10 |
| 16 | 12 |
| 25 | 14 |
| 35 | 16 |
| 16 |
Note: Single core wires less than 10mm can be installed directly using the bending circle method.
Appendix A7 Wire phase sequence arrangement
| Phase arrangement/sequence method | Vertical | Horizontal | Front and back | Signal color |
| A | Main | Left | Distant | Yellow |
| B | Quite | Quite | Average | Green |
| W | Bottom | Right | Zoom in | Red |
| Neutral Line | Much inferior | Finally | Closer |
Note: The above is noted on the front of the case. (Special cases may not follow this table, but must be noted)
Appendix A6 Bolt connection hole dimensions for rectangular busbars
| Legend | Dimensions (mm) | Components | |||||||||||
| A | B | D | F | AND | W | ￠ | Diameter | Screw | Nut | Washing machine | Elastic washer | ||
|
15 20 25 30 40 |
40 50 50 60 80 |
10 12 12 15 20 |
20 26 26 30 40 |
7 11 11 13 13 |
M6 M10 M10 M12 M12 |
two | two | 42 | ||||
|
50 60 |
75 90 |
14.5 17 |
14 17 |
22 17 |
23 28 |
13 | M12 | 3 | 3 | 63 | ||
|
80 100 |
80 100 |
17 | M16 | 4 | 4 | 8 | 6 | |||||
|
15 20 25 20 25 25 35 40 30 40 |
15 15 15 20 20 25 25 25 30 30 |
7 7 7 11 11 11 11 11 13 13 |
M6 M6 M6 M10 M10 M10 M10 M10 M12 M12 |
1 | 1 | two | 1 | |||||
Appendix A6 (2) Hole Size for Rectangular Bus Bolt Connection
| Legend | Dimensions (mm) | Components | ||||||||||
| A | B | D | F | AND | W | ￠ | Diameter | Screw | Nut | Washing machine | Elastic washer | |
|
40 50 60 60 |
40 50 50 60 |
11 14 14 17 |
11 14 17 17 |
18 22 26 26 |
18 22 22 26 |
11 13 13 13 |
M10 M12 M12 M12 |
two | two | 4 | two |
|
30 40 30 30 40 40 50 50 50 50 60 60 60 60 80 80 80 80 100 100 100 |
12 12 15 20 15 20 20 25 30 40 30 25 30 40 30 40 50 60 40 50 60 |
7 10 7 7 10 10 12 12 12 12 15 15 15 15 20 20 20 20 20 25 25 25 |
16 20 16 16 20 20 26 26 26 26 30 30 30 30 40 40 40 40 50 50 50 |
5.5 5.5 7 7 7 7 11 11 11 11 11 11 13 13 13 13 13 13 13 13 13 |
M5 M5 M6 M6 M6 M6 M10 M10 M10 M10 M10 M10 M12 M12 M12 M12 M12 M12 M12 M12 M12 |
two | two | 4 | two | ||
|
80 80 100 |
80 80 100 |
17 | M 16 | 4 | 4 | 8 | 4 | ||||
Appendix A8 Electrical clearance, creepage distance and spacing distance (mm)
| Rated insulation voltage（V） | Electrical Release | Escape distance | ||
| 63A and below | More than 63A | 63A and below | More than 63A | |
| V≤60 | 3 | 5 | 3 | 5 |
| 60＜V≤300 | 5 | 6 | 6 | 8 |
| 300＜V≤660 | 8 | 10 | 10 | 12 |
Minimum distance between the electrical equipment of the primary circuit and the ground.
| 3KV | 6KV | 10KV | 35KV | ||
| The distance between bare conductors of different phases and between bare live parts to the grounded structure. | 75 | 100 | 125 | 300 | |
| The distance from the energized part of the bare conductor to | Front metal cover plate | 105 | 130 | 155 | 330 |
| Drive Rod Bare Belt | 100 | 120 | 130 | 320 | |
| The part of the energized bare conductor to the mesh seal plate or mesh door | 175 | 200 | 225 | 400 | |
| Height from bare unshielded conductor to ground slab (floor) | 2500 | 2500 | 2500 | 2500 | |
