GKW Isolated Phase Busbar provides the permanent electrical connection between the generator and the generator transformer and are rated for between 3.6kV and 36kV, with currents up to 40kA. GKW IPB systems are specified by the foremost electrical equipment suppliers and project management contractors, and by national power authorities.
INTERNATIONALLY SPECIFIED—ADAPTABLE TO MEET EXTREME GEOGRAPHIC AND CLIMATIC CONDITIONS
SYSTEMS FOR ALL FORMS OF POWER GENERATION
GKW is a world leader in every aspect of design, manufacture, supply, installation and commissioning of all types of busbar systems. GKW Isolated Phase Busbar (IPB) been supplied for fossil fuel, hydro electric and nuclear power stations, and installations can be found in each of the world’s six continents.
Experience gained in a multitude of operating conditions ensure that GKW IPB meets every requirement for reliability and performance and provides a number of key factors:
> Minimum risk of phase-to-phase short circuits
> Ability to withstand high “through fault” currents
> Sustained integrity of the dielectric medium
> Prevention of induced currents in adjacent metalwork
> Easy, safe and secure interfacing with circuit breakers and other fixed plant
The GKW IPB design is a proven concept, using a cylindrical aluminium conductor for each phase supported within an aluminium enclosure by insulators available in both epoxy resin and porcelain.
The conductor support systems are spring loaded to allow the conductor to move during normal operation. In the event of a fault, this also allows for concentric movement of the conductors in relation to the magnetic centre of the IPB enclosure, preventing the insulators from being subject to potentially damaging stresses generated by the fault current.
The enclosures of the three phases are bonded together at both ends with at least one end connected to the station earth.
Where necessary due to long lengths, laminated expansion joints are used along the conductors and enclosures to allow for thermal expansion.
Modern machines, equipment and techniques are used in the manufacture of GKW Isolated Phase Busbar systems. Welding is carried out by fully certified operators who have satisfied the requirements of weld tests.
WHERE POSSIBLE THE UNITS ARE SHIPPED TO SITE PRE-ASSEMBLED TO MINIMISE ON-SITE WORK
RELIABILITY AND SAFETY
GKW IPB is fully tested and designed to comply with the following standards:
BS 159:1992, BS EN 62271-200:2012 and IEEE Std C37.23-2015.
Type Testing of equipment is undertaken at independent laboratories in the United Kingdom and overseas. During the manufacturing cycle all GKW production is subject to strict quality control procedures.
GKW also hold full accreditation to quality assurance standards BS EN ISO 9001 and 14001.
Design calculations for Isolated Phase Busbar systems assume that the heat generated in the conductor is dissipated by conduction and radiation, with the large diameter busducts capable of dissipating more heat than smaller busbars. The maximum temperature rise during operation at any point on the conductors does not exceeed 65oC over an ambient of 40oC at the rated current.
For installations up to 23,000 amps standard designs are naturally air cooled. For higher current levels (i.e. up to 40,000 amps) and generators larger than 660MW, GKW have type tested designs to combat the heat produced by installing complex and reliable Forced Air and Water Cooled systems. These have been developed to eliminate the complexities of some systems and ensure that the busbars operate in clean and dry conditions.
Terminal Connections design results from exhaustive evaluation of terminal connections and associated components, to both the generator and the generator transformer terminals. As a result, GKW can provide cost effective terminal connections suitable for interface with all major equipment manufacturers.
Voltage Transformer cubicles of various design can be provided, permitting safe isolation while the system is on load. Interlocks prevent opening until the system has been isolated and earthed.
Wall Seals are available to provide a weather-tight seal for environmental protection. The seals are designed to allow the busbars to expand and contract during operation. Insulator bushings may also be specified to seal the annular space between the conductor and the enclosure.
Spring Loaded Insulators allow concentric movement of the conductor within the enclosure in the event of a short circuit. Insulators are fully type tested and designed to meet BS 3816. Insulators are usually manufactured from epoxy resin but alternative materials including porcelain are available.
Sealed expansion joints. Aluminium laminated expansion joints are incorporated to maintain full continuity. Neoprene rubber bellows seal the site joint while also allowing easy access to the connections for maintenance.