Transformer is remanufactured better than new

Edited by the Engineeringtalk editorial team Dec 17, 2007

Largest UK transformer to date is factory remanufactured by ABB's power systems service team.

ABB's fast-track transformer remanufacturing service has enabled ScottishPower to bring its 400MW Shoreham Power Station back on-line in record time after it suffered a major fault in its GSU (generator step-up unit) transformer.

The 226 tonne transformer is the largest UK unit to date to have been factory remanufactured by ABB's power systems service team.

The entire project, including transportation to the factory in Norway, was completed in nine months - well under half the time required to source a new transformer - and at around 75% of the cost.

The single 470MVA 21/132kV GSU transformer is vital to the operation of the Shoreham CCGT (combined-cycle gas turbine power station) in West Sussex.

It steps up the 21kV terminal voltage produced by the power station generators to the 132kV required for the transmission grid.

Without the GSU transformer, Shoreham Power Station cannot produce power, and each day of lost generation represents a significant loss of income to ScottishPower.

The project began in January 2007 when the GSU transformer at Shoreham failed unexpectedly.

ABB's power systems service team was called in, and after carrying out a series of diagnostic tests it was clear that there was a major failure in the transformer windings.

Following discussions between ABB and ScottishPower it was agreed that the most cost-effective solution would be for ABB to take the transformer back to its specialist repair factory in Drammen, Norway where it would be remanufactured to create what is essentially a new transformer within the existing shell.

ABB stripped the transformer ready for transportation and then called in its specialist transport contractor to arrange for it to be transported to the nearby Port of Shoreham, and then by sea to Drammen.

At the factory the transformer was detanked and stripped down completely to its component parts.

It was now that ABB was able to confirm that the diagnosis of a winding failure was correct.

A full three-phase rewind was carried out, and on ABB's advice ScottishPower agreed that the re-manufacture should be carried out to the very latest standards for energy efficiency and reliability - resulting in a transformer that is now "better than new".

On completion of the FATs (factory acceptance tests), ABB's specialist transport contractor transported the transformer back to Shoreham where it was re-installed and commissioned for service by ABB.

In mid-October the GSU transformer was back on-line, ahead of schedule, enabling Shoreham Power Station to begin generating power again after an interval of only nine months.

Gary Murray, Shoreham Power Station Manager, says: "The transformer remanufacturing project has been a tremendous achievement thanks to the hard work, dedication and team work shown at every stage, both on site and in the factory".

"We especially appreciate the way that ABB responded to the urgency of our situation by rescheduling its factory workflow to bring this project forward".

"As a result, the station has been returned to service safely and even earlier than expected".