On 5 May the Powerformer at Porsi hydro plant in Sweden began delivering electricity directly to the local grid at a rated voltage of 155kV.
The Porsi unit is owned by Vattenfall, and is situated on the Lule river in Northern Sweden. It has the third high-voltage generator based on PowerFormer technology. The first was installed in Porjus, also in northern Sweden, in 1998 and has already accumulated more than 12,000 hours of service. The second, a thermal unit, was delivered to the customer in 2000. alstom is soon to hand over a fourth unit.
The Porsi high-voltage generator, which replaces an older machine from 1950, is connected directly to 155kV switchgear. The Powerformer design eliminates the need for step-up transformers and medium-voltage switchgear. Conventional generators have rated voltages of around 10kV.
