Renewable Energy
New coils boost output of geothermal generator
A project to overhaul one of the Fuji 37.5MW generators required careful planning to ensure the minimum of disruption.
El proyecto de reacondicionamiento de uno de los generadores Fuji 37.5 MW requiere de una planificación cuidadosa para garantizar un nivel de interrupción mínima.
Ein Projekt zur Überholung eines der Generatoren vom Typ Fuji 37,5MW erforderte eine sorgfältige Planung, um Unterbrechungen zu minimieren.
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Fig. 1. The Palinpinon geothermal power plant is located in Valencia, Negros Oriental, in the Philippines, where it produces a combined output of 192MW.
Photo: Mike Gonzalez.
he Palinpinon geothermal power plant is located in Valencia, Negros Oriental, in the Philippines, where it produces a combined
output of 192MW. Plant 1 was originally commissioned in 1983 and having reached 30 years in service, one of the generators was scheduled for a rebuild with new coils. Te contract to rewind the generator was won by Sulzer, with the task of designing and constructing the new coils going to its Service Centre in Birmingham, UK.
Te site comprises two power plants, the first containing three 37.5MW generators and the second containing four 20MW generators. Demand for electricity in the local area is high, with the site operating at full capacity and therefore it is essential that the generators are properly maintained and operating at their maximum potential. Te project to overhaul one of the
Fuji 37.5MW generators required careful planning to ensure the minimum of disruption. Using the large company database, combined with the OEM
drawings for the generator, the Sulzer Service Centre was able to design the new coils as well as a set of wooden formers to replicate the stator, which would be used later to check the shape of the coils during the manufacturing process. Using the latest CAD software, the coils can be precisely formed to ensure an exact fit in the stator slot, making the installation process more efficient. With its in-house copper rolling mill, the Service Centre is able to maintain round-the-clock coil production to meet even the tightest deadline, using air freight when necessary to minimise the repair timetable. Every coil is tested in the dedicated test cell with the results recorded and kept in the engineering archives. Testing includes tan δ, which relates to the power factor of the coils as well as strand-to-strand short circuit testing and the outer corona protection (OCP) surface resistance measurement. Back in the Philippines, the dismantling process of the generator began and it was clear that 30 years of continuous operation had taken its toll. Te coil support blocks had started to fail and needed to be replaced with new components, manufactured from G11 material, a fibreglass epoxy laminate with excellent electrical insulating properties. As the process continued and the stator was removed, it became apparent that there had been a high degree of partial discharge. Damage was also found to the middle separator strip and the semi-conductive side packing. All of the evidence relating to the historic damage was documented and will form part of the final report that is presented to the client at the end of the project. Te stator core was completely stripped, cleaned and tested before the new coils could start to be inserted, blocked and braced. With all the new coils in place and the new caps fitted,
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