Shaft generators were previously mainly used in propulsion systems with engines and propellers running at a constant speed (CRPM mode). The best overall propeller efficiency is achieved by optimizing the relationship between pitch and rpm. Operating the vessel below its design speed, at constant rpm but with a lower pitch, leads to decreased propeller efficiency. However, reduced rpm results in a frequency reduction of the shaft generator, potentially causing the electric system onboard to malfunction.

Our custom-made net frequency stabilizer system NFS allows the shaft alternator/generator to operate at variable speeds, while still providing a stable frequency and voltage to the main switchboard.

The unit has an active front-end drive. It can be dimensioned to support full electric loads or partial capacity for selected consumers with stable frequency. In the case of partial capacity, a bypass function for full load scenarios in constant rpm can be applied.