Bus Ducts Verticals


Bus ducts or bus bars are used to carry very high current between the generator and associated transformers, in the power stations. Bus duct forms an electrical link between generator , transformers and associated equipment's. it is an assembly of bus bars with associated joints ,connections and supporting insulators within a grounded metal enclosure. Bus bars are thick metal connectors, usually of aluminium , which carry large current up to 10 KA. The conductors are metal enclosed, usually aluminium to provide safety and reliable operation. Aluminium has been used for the enclosure, as well as it reduces the magnetic losses. Aluminium is being used increasingly as bus bar material, in power stations, distribution boards, switchgear, etc. one of the main reasons for this is that it is cheaper to use than copper and making allowance for the light metal's.

Types of Bus Duct's

There are three types of bus ducts

  • Isolated phase bus duct
  • segregated phase bus duct
  • Non segregated phase bus duct


An IPBD most commonly used for large power generating unit and popularly known as generator bus duct , serves as an interconnection between generator and it's associated auxiliary equipment . Conductors are air insulated and supported in the centre of an enclosure by strategically arranging the insulators . phase to phase circuits are eliminated and no current is induced in the steel work, cable pipes or other metal structures in close to proximity bus duct.

In Isolated Phase Bus duct each phase conductor is enclosed by an individual metal housing and separated from adjacent phase conductor housing by an air space. Each phase conductor is mounted in an individual enclosure and is carrying a much higher current for a given permissible temperature hence it has a large eat dissipation as compared to segregated and non-segregated phase bus duct.


Metal enclosed bus duct in which all the phase conductors housed in common metal enclosure and segregated by metallic barrier between phases. Segregated phase bus duct is generally employed in medium voltage systems and serves as interconnection between the switchgear and transformer. The segregated phase bus duct comprises of three phase conductors running along with barrier made of aluminium alloy. The non-magnetic barrier provided between phase conductor reduces forces during phase to phase faults and also helps in reducing temperature rise.


Metal enclosed bus duct in which all phase conductors are in common metal enclosure with only air barrier and physical separation between the phases. NSPBD serves as an interconnection between 1.1KV switchgear/indoor power control centre (PCC)/motor control centre(MCC) and its auxiliary transformer. It is also used for trunking connection between two separate switchgear/PCC/MCC, wherever applicable.


The bus duct provide a means for carrying high current. It provides high system reliability. The type and rating of bus duct shall be as per system requirement.

The design of bus duct is based on following factors.

  • The continuous current rating.
  • Maximum system voltage.
  • Maximum dynamic and transient forces it may be subjected to during its life span.
  • The dielectric requirement of the system.
  • Climatic conditions.

We offer a wide range of industrial and generator bus ducts custom made to suit the specific requirements of various applications including

Conventional Non Segregated Phase Bus Ducts. (Rating 415V, 50hz Ranging From 800 Amps To 3200 Amps) Low Reactance Interleaved Bus Ducts. (Rating 415V, 50hz Ranging From 3200 Amps To 5000 Amps) Segregated Phase Bus Duct. (Rating 3.3, 6.6, 11 kV, 50hz Ranging From 1250 Amps To 5000 Amps)