Design and Placement of Busbars
– Busbars can have a cross-sectional area ranging from 10 to 2,000 square millimeters.
– Different shapes of busbars, such as flat strips, solid bars, and hollow tubes, are used based on the application.
– Hollow or flat shapes are preferred for higher-current applications due to the inefficiency of thick busbars caused by the skin effect.
– Hollow sections have higher stiffness compared to solid rods of equivalent current-carrying capacity, allowing for greater spans between busbar supports in outdoor switchyards.
– Busbars must be rigid enough to support their own weight, withstand mechanical vibration, earthquakes, precipitation, thermal expansion, and magnetic forces.
Distribution Boards and Busways
– Distribution boards split the electrical supply into separate circuits at one location.
– Busways, or bus ducts, are long busbars with protective covers that allow new circuits to branch off anywhere along the busway.
– Busbars may be supported on insulators or wrapped in insulation.
– Busbars are protected from accidental contact by metal earthed enclosures or by being elevated out of normal reach.
– Power neutral busbars may also be insulated to ensure safety grounding potential is always zero.
Connection and Joints
– Busbars are connected to each other and to electrical apparatus through bolting, clamping, or welding.
– High-current bus sections have precisely machined matching surfaces that are silver-plated to reduce contact resistance.
– At extra high voltages, special connection fittings are used to minimize corona discharge, radio-frequency interference, and power loss.
– Joints between bus sections in outdoor buses at voltages over 300 kV are particularly susceptible to corona discharge.
– Connection fittings designed for these voltages are used to mitigate the effects of corona discharge.
Related Concepts
– Electrical busbar system
– Bus duct
– Wire bridge
– Jumper (computing)
References and Further Reading
– ‘Copper for Busbars: Guidance for Design and Installation’ (PDF) from Copperalliance.org.uk
– ‘What is a Busbar & Other FAQs on Electrical Copper Busbars’ from Starlinepower.com
– IEC 60050 – International Electrotechnical Vocabulary – Details for IEV number 605-02-22: flexible busbar
– IEC 60050 – International Electrotechnical Vocabulary – Details for IEV number 605-02-21: rigid busbar
– ‘Protective Relaying Theory and Applications’ by Walter A. Elmore
– Wikimedia Commons has media related to Busbars
– ‘Ensuring a Good Bus Duct Installation’ by John Paschal Source: https://en.wikipedia.org/wiki/Busbar
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (August 2014) |
In electric power distribution, a busbar (also bus bar) is a metallic strip or bar, typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution. They are also used to connect high voltage equipment at electrical switchyards, and low voltage equipment in battery banks. They are generally uninsulated, and have sufficient stiffness to be supported in air by insulated pillars. These features allow sufficient cooling of the conductors, and the ability to tap in at various points without creating a new joint.
