A copper bus bar is a conductor, usually made of pure copper or copper alloy, and is usually rectangular in cross-section, but can also be circular or custom shaped. In electrical engineering, its main role is ascurrent carriers andbus, used to transmit and distribute large currents.
Its main purposes include:
Transmission of high currents: Copper’s excellent electrical conductivity allows it to effectively transmit high currents and minimize energy losses.
Current distribution and collection: In power distribution equipment, buses distribute current from the main power source to various branches or collect current from multiple power sources to a single point.
Voltage stabilization: Due to its superior electrical conductivity, it effectively reduces voltage drop and ensures voltage stability.
Connecting electrical components: It serves as a connection bus inside electrical equipment, connecting various components (such as circuit breakers, contactors, transformers, etc.).
Heat dissipation: Copper itself has good thermal conductivity and helps dissipate the heat generated during current transmission.
Copper busbars are widely used in almost all areas requiring high current transmission and distribution. These areas mainly include:
Power transmission and distribution systems:
Distribution cabinet, switch cabinet, control cabinet: Used as an internal connecting bus for power transmission and distribution.
Transformers, generators: used for high-voltage and low-voltage connections.
Busway system: Replace traditional cables for high current transmission in high-rise buildings, factories and similar environments.
New energy field:
Solar photovoltaic power generation systems: Current collection and transmission within junction boxes and inverters.
Wind power generation: Power connections within a wind turbine.
Energy storage system: connection between battery modules and battery packs and connection of inverters.
Electric vehicles (EVs) and charging infrastructure:
Electric vehicle battery pack: Series and parallel connections within battery modules and battery packs.
Motor controller: Used for high current input and output connections.
Charging piles/stations: Power transmission within high-power charging equipment.
Industry and infrastructure:
Data centers: Power transmission in high-performance server racks and power distribution units (PDUs).
Industrial machinery and automation: Power supply and control systems in large industrial equipment.
Transportation (railway, subway): power supply and distribution system.
Electrolysis and electroplating industry: high-current conductors for electrochemical processes.
Building electrical system:
Primary power distribution for commercial and residential buildings.
The choice of copper and aluminum busbars depends on specific application requirements, budgets and performance considerations. Here is a comparison of their advantages and disadvantages:
| features | copper busbar | aluminum bus |
| conductivity | Excellent (approximately 100% IACS) –Lower resistance and less heat generation under the same current. | Good (about 61% IACS)-higher resistance and more heat is generated at the same current. |
| power | high mechanical strength –It is not easy to deform and has stronger resistance to short circuit. | Lower mechanical strength-easier to deform and requires more support. |
| power | high mechanical strength –It is not easy to deform and has stronger resistance to short circuit. | Lower mechanical strength-easier to deform and requires more support. |
| corrosion | good corrosion resistance –A protective oxide layer is naturally formed; electrochemical corrosion is not easy to occur with most common connection materials. | Easily oxidizes (forming a non-conductive oxide layer), and the connection requires special surface treatment (such as tin plating). Galvanic corrosion is prone to occur in direct contact with copper. |
| weight | Heavier (density approximately 8.9 g/cm³) | lighter (Density is about 2.7 g/cm³)-With the same conductivity, the weight is about 1/3 of that of copper. |
| cost | higher material costs –Due to the rise in copper prices. | Material costs are lower-often more economical. |
| thermal expansion | Lower coefficient of thermal expansion-more stable in temperature fluctuations. | Higher coefficient of thermal expansion-expansion joints need to be given more consideration. |
| contact | It is easier to connect and the joints are not prone to creep or cold flow. | The connection points are more prone to creep (cold flow) and require spring washers or retightening. |
| ductility | Excellent ductility and easy to bend and manufacture. | Good ductility, but not as good as copper. |
| overall performance | Excellent electrical and mechanical propertiesLong-term reliability. | For many applications, performance is acceptable and cost-effective. |
Why choose copper? For applications requiring high reliability, high current density, compact design, long life and low maintenance, copper is often the first choice despite the higher cost.
Why choose aluminum? For cost-sensitive projects, when weight is a critical factor (such as overhead transmission lines), aluminum is a viable option if space permits and a larger cross-sectional area can be used to compensate for lower conductivity.
Choosing the right copper busbar size and specification is critical for safe and efficient operation. Key factors to consider include:
Definition: The maximum continuous current that the bus duct can safely carry without exceeding its allowable temperature rise.
Factors affecting current carrying capacity:
Cross-sectional area: The larger the area = the greater the current carrying capacity.
Material: Copper with the same cross-sectional area has a higher current carrying capacity than aluminum.
Ambient temperature: The higher the ambient temperature, the lower the current carrying capacity.
Installation method: Open-air installation vs. enclosed installation (e.g., in cabinets); horizontal installation vs. vertical installation. Enclosed installation and poor ventilation can reduce current carrying capacity.
Number of buses: If multiple busbars are used in parallel, current sharing needs to be considered and a derating factor may be applied.
Surface treatment: Plating (e.g. tin, silver) will affect heat dissipation.
Calculation: The current carrying capacity is usually determined based on the manufacturer’s table or calculated using a formula that considers resistivity, heat dissipation surface area and allowable temperature rise.
Definition: The difference between the operating temperature of the bus and the ambient temperature.
Importance: Excessive temperatures can damage insulation, shorten component life and increase energy losses.
Restrictions: Industry standards (e.g., IEC, NEMA) specify the maximum allowable temperature rise for different applications and insulation classes.
Definition: Voltage decreases along the length of the bus due to bus resistance.
Importance: Excessive voltage drops can reduce efficiency, affect equipment performance and cause power quality issues.
Calculation: ΔV=I×R, where I is the current and R is the bus resistance (depending on length, resistivity, and cross-sectional area).
Notes: For long-term operation or critical applications, minimizing voltage drops is critical.
Busway must be able to withstand mechanical and thermal stresses caused by short circuit faults without causing permanent damage or dangerous deformation. This requires calculating peak short circuit currents and ensuring that the strength and support system of the bus duct are adequate.
The bus bar must be strong enough to support its own weight and withstand electromagnetic forces during normal operation and short circuits. Appropriate support insulators and support structures are crucial.
Space limitations:
The physical size of the bus bar must be suitable for the available space within the equipment or enclosure.
Balancing performance requirements with budget constraints.
Selection Guide:
Determine the maximum continuous operating current.
Determine your applicationAllowable temperature rise (usually determined by standards or insulation class).
According to current carrying meter or formulaCalculate the required cross-sectional area, taking into account ambient temperature and installation method.
check Anticipate the voltage drop of length and current to ensure it is within acceptable ranges.
Verify system fault currentShort-circuit endurance.
Consider mechanical support and thermal expansion.
Refer to manufacturer’s data sheet and related industry standards (such as IEC 60439, UL 891). It is best to always leave a little safety margin.
Please feel free to contact [email protected]contact us –Our technical team will be happy to tailor the solution to your specific needs.
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