Plant & Works Engineering
Power provided for generator test
Published:  08 July, 2011

Aggreko, the temporary power and temperature control solutions company has provided power for First Hydro to test a newly manufactured generator stator (the stationary part of the generator that houses the rotor) at the Ffestiniog plant in the Snowdonia region of Wales. First Hydro, which operates two power stations in North West Wales, is part of a joint venture between International Power plc and Mitsui & Co. Ltd. and this work is part of a planned refurbishment at the power station.

 Ffestiniog’s four powerful AEI-manufactured generating units, each coupled with turbines and pumps, are located below the Moelwyn mountains and produce 360 MW of electricity from the Stwlan reservoir.

The facility was fully commissioned in 1963 to act as a peaking station to support the UK’s plans at the time to invest in nuclear energy. Today, the station still acts as a key ‘top up’ power generator to the National Grid.

 Dewi Griffiths, electrical engineer at First Hydro, said: “This was no simple ‘plug in and play’ scenario, and testing the equipment presented us with some significant challenges.

“Firstly, we needed to assess whether we could use power from one of the other generator motors to carry out the HV flux text. In the end we decided to opt for the outsourcing route, working with Aggreko, as this meant we could continue to fulfil our obligations to the National Grid during the testing period. Secondly, once we’d decided to use generators to power the flux test, we needed to choose a partner that had the experience to carry out this type of work. Aggreko was the natural choice.”

Aggreko used three 1250 kVA diesel generators, working in synchronisation, to set up the test rig, taking just a day for installation and half a day for decommissioning. The generators were set up to produce very low voltage that was run through a transformer to step up the power to 3.3 kV. This was then connected to a cable, which had been coiled around the stator bore to produce a magnetic field, thus simulating the conditions of the power-generating process.

Marcus Saul, sales engineer at Aggreko, said: “This complex set-up is designed to identify potentially damaging hot spots on the core packets of the stator. In this instance, none were evident, so final commissioning could go ahead in the autumn of 2010.

“Apart from the technical nature of the project, we were also faced with the challenge of transporting three of our largest generator sets to a remote location in the mountains of Snowdonia National Park.

“This project illustrates Aggreko’s capability to provide cost-effective solutions to complex technical problems, initially by working closely with the customer to fully understand the issues involved and then using Aggreko’s considerable skills and experience to identify the best option for commissioning the equipment as quickly as possible, thus saving time and money.”


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