A friend working on a ship recently had a interesting question about frequency of generator driven by main engine.

The ship was built two years ago, it has two main engines, two output ends of each gearbox, one of which is equipped with a shaft generator. He noticed one specification: the Axle generator can be used under any working conditions during navigation. I was wondering a problem: different working conditions, different engine speeds, different speeds of the shaft generators, different speeds of the generators, how to ensure that the output power is 60 or 50Hz, diesel generators are different, it has a servo and its mechanism can adjust the engine to a constant speed, but how does the axle generator realized it?

Engineer from Deyuan Marine Fitting Co.,Ltd accordingly gave answers as below, hope to make some help for whom have the same confusions: 

There are three cases:

1, CPP propulsion, the host is a constant speed, drag the shaft with a generator through the speed-increasing gearbox, so it can send a stable frequency of electricity; the shaft can be installed at the free end or the drive end of the mainframe, according to actual needs;

2. FPP propulsion, the main engine's speed change is relatively large, the PTO gear wheel box is replaced by 'constant gear box' to drag the shaft generator; the shaft can be installed on the free end or the drive end of the mainframe, according to actual needs ;

3. FPP propulsion, the main engine's speed change is relatively large, the PTO's gear wheel box drags the shaft with the generator, and the electricity generated by the generator is adjusted by the AC/DC-DC/AC inverter to meet the standard AC requirements. The shaft can be installed at the free end or the drive end of the main engine; or according to actual needs, the generator can also be mounted on the shaft without a gear box; the electric power generated by the generator is adjusted by the AC/DC-DC/AC inverter. , AC power that meets the standard requirements;

 

 

In the second and third cases above, the shaft belt can be connected to the diesel generator for a long time;

In the first case above, the shaft can be used for short-term grid-connected load transfer with the diesel generator, and the shaft is used during normal sea navigation;