Constant Frequency Generator

Constant Frequency Generator – CFG
Naust Marine’s CFG solution can be used onboard vessels where main engine speed is variable (floating frequency). The benefits of having such a setup is that the shaft generator can be used to power the hotel and auxiliary users without the need to start a diesel genset. This is especially true for fresh fish / catcher vessels where there is no power heavy factory.

Using the CFG:

  • The CFG’s function is to provide constant voltage and frequency (400V/50Hz or 480V/60Hz) to a second, constant frequency, bus bar regardless of the voltage and frequency of the shaft generator. This works like a diesel generator driven by the main engine, without limiting variable speed of the main engine.
  • CFG can be synchronized and run in parallel with other gensets on board, if needed.
  • When the CFG is in use, its breaker (CB2) will connect the two bus bars while main bus tie (CB3) remains open allowing for constant frequency on the second bus bar when only using the shaft generator.
  • The CFG can supply the second bus bar by itself or it can run in parallel with the auxiliary generators. To be able to run the CFG and Auxiliaries together, a PMS unit for synchronization and load sharing must control the CFG as if it were an extra auxiliary generator (see AutoGen).

Benefits of using CFG on floating frequency

  • Lower fuel consumption because it is possible to optimize main engine RPM and propeller pitch when towing.
  • No need to run diesel generator set during much of the vessel operation
  • Choosing/replacing equipment for the vessel is made easier since it will not need to be able to handle variations in voltage and frequency.
  • Some equipment onboard will need to be supplied with constant 230V/50Hz. In this case, a 400/230V transformer can be added on the second bus bar instead of installing a rotating 230V clean power generator.

CFG diagram.png