Siemens Energy has developed the new gas-insulated medium-voltage switchgear, NX Plus C Wind. The gas-insulated switchgear deployed by Siemens to date has supported wind turbines at 24 kV. The new NX Plus C Wind switchgear operates at a voltage of 36 kV. It is also a more compact design than the previously built 36-kV Siemens switchgear and can be readily accommodated in the tower of a wind turbine.
Siemens developed the medium-voltage switchgear for deployment in wind farms. It is installed in the base of the wind turbine tower and therefore has to fit through the door. Because there is limited space in the tower, the 36-kV switchgear is compact: Compared to a conventional 24-kV switchgear, the new unit is 1000 mm deep, and thus 250 mm shorter. Moreover, stringent demands were made of the switchgear’s reliability. In the event of harsh weather conditions the switchgear in the wind turbines may often be inaccessible for days or even weeks.
In most applications the wind turbine, with its generator, supplies electrical energy at a voltage of 690 V. A downcircuit converter matches the frequency to that of the wind farm’s network and ensures a stable voltage level. A transformer steps this up to 30 kV or 33 kV to keep transmission losses low. The wind turbine is ultimately connected with the wind farm’s network via the circuit-breaker bay.