Busbar power distribution systems are very popular, but there are choices to be made, and one of those is which busbar material to use. Aluminium is the major alternative to copper. John Clarke discusses the issues.
Over the last 50 years, busbar power distribution systems have increased in versatility and sophistication and are now widely regarded as the first-choice solution for power distribution projects in most industrial and commercial applications. It’s not difficult to see why. When compared to conventional hard-wired forms of power distribution, the latest generation, busbar systems with aluminium conductors have several key benefits.
These benefits are:
- They are lighter than traditional busbars.
- They are easier, quicker and cheaper to install.
- They are manufactured using high quality components and have built-in safety features.
- They also offer flexibility in design and can be easily adapted and modified as future requirements change.
Aluminium or copper?
With all this in mind, perhaps the question is no longer whether busbar systems are better than conventional hard-wired systems, but rather which busbar trunking to use – aluminium or copper?
Aluminium has long been regarded as ‘the poor relation’ to copper as an electrical conductor, and consultants have been reluctant to specify systems with aluminium conductors – often basing their decision on outdated information or misinformation.
Over the past few years, however, significant advances have been made and the aluminium used in busbar trunking systems today is an exceptionally high performance product that offers cost-savings, excellent mechanical strength, heat stability and thermal conductivity characteristics, which compare very favourably with those of copper:
Cost – On the world’s commodity market, aluminium tends to have a more stable value and, unlike copper, is not so sensitive to the ‘ebb and flow’ of consumer demand, political uncertainties and other economic factors. As a result, aluminium has consistently provided huge cost savings for specifiers and contractors. This is obviously a major consideration for all concerned in the highly competitive market of power distribution projects. The biggest advantage that aluminium has over copper is therefore quite simply – cost!
Weight – Aluminium is up to 70% lighter than copper. This not only saves money on transportation, but also on the time, effort (and therefore cost) of installation.
Conductivity – Generally, conductivity of copper is better than aluminium (aluminium’s conductivity is 62% that of copper). However, the weight of copper is three times that of aluminium, which – as previously stated – has a significant impact on the cost of installation and transportation. When you compare an aluminium system against a copper-based system of equal size and weight, aluminium scores twice as conductive as copper.
Jointing – In the past, specifiers have been critical of the fact that aluminium is susceptible to oxidisation, which affects the contact conductivity at the joint. Manufacturers of busbar systems have overcome this factor by completely electro-tin plating the conductor bars, which eliminates any problems associated with jointing dissimilar metals.
Safety – Unlike ferrous metals, aluminium does not generate sparks when used in combination with other metals, making it the ideal choice for use in potentially inflammable or explosive environments. Zucchini uses zinc and tin-plated aluminium in its busbar construction, which makes the aluminium longer lasting and easy to work and maintain.
Non-magnetic – As aluminium is non-magnetic, it is ideal for use in applications that need minimum magnetic interference. These include high-voltage applications as well as electronics.
Mechanical strength – Aluminium alloys have a mechanical resistance of 60 to 530 Newton/mm². This is more than sufficient.
I hope that readers involved with power distribution projects give further consideration to the advantages of specifying aluminium busbar systems – particularly in terms of performance, safety and cost.