New medium-voltage switchgear and motor starters from the Merlin Gerin brand of Schneider Electric are revitalising the wind tunnel installations at one of the UK’s leading fluid dynamics research facilities – Cambridge University’s renowned Whittle Laboratory. Airflow in one of the laboratory’s largest wind tunnel installations is provided by two fans, one equipped with a 500hp motor, the other with a 1,000hp motor. Both motors operate at 3.3kV. The existing electrical equipment associated with the motors was, however, more than 40 years old and, in recent years, had become unreliable and difficult to maintain.
In addition, the configuration of the equipment was such that only one of the motors could run at a time, which placed severe restrictions on operational flexibility.
Invited to devise an upgrade which would improve reliability and flexibility, Schneider Electric developed a solution incorporating a new 11kV switchboard to receive incoming supplies from the public electricity network, a new 11kV to 3.3kV transformer, and a new motor starter panel with capacity for future expansion.
For the 11kV switchboard, which comprises two incoming sections and two transformer feeders, products from the Merlin Gerin Genie Evo range were selected. This pre-engineered equipment, based on demountable vacuum circuit breakers, is economical, easy to specify, and fully complies with requirements for direct connection to the local utility’s supply network.
Also supplied by Schneider Electric, the transformer is a cast resin type, chosen for its F1 fire behaviour certification – the best rating available for distribution transformers – and for its totally maintenance-free operation.
To control the 3.3kV motors, two Merlin Gerin Motorpact direct-on-line starters are used, in a board which has spare cubicles to accommodate future extensions to the wind tunnel installation. Fully internal arc rated to ensure operator safety, Motorpact medium-voltage starters have very low maintenance requirements, and feature an energy efficient design which reduces losses and minimises the equipment operating temperature.
Since all major items of equipment for this project were supplied by the brands of Schneider Electric, the implementation and commissioning of the new electrical installation were fast and problem free.
The increased capacity of the new equipment means that Whittle Laboratory can now run both fans simultaneously, and that further fans can be added easily and inexpensively should the need arise. In addition, reliable operation is now assured with an electrical installation that meets the latest safety and environmental requirements, and which needs almost no maintenance.