eop   |    Variable speed and start-stop function

img-title-whiteIf there are two or more generating sets on board it is obvious which advantages can be reached by operating just one set with variable speed at the point of required power with the best possible efficiency instead of running multiple sets at a very low load.

Optimized fuel consumption due to variable speeds and start-stop function for generating sets.

Up to now electric ship networks are typically operated with a common voltage and frequency. Thus, the combustion engines driving the auxiliary sets must run with a synchronous speed. There is no chance to make use of variable speeds corresponding to actual power demands.


With the technology developed by E-MS the engines driving generating sets can now – at any time – run load dependent with the speed achieving the best efficiency possible. They may be used either at the speed of best efficiency or according to the demand of electrical energy on board with the respective speed whichever best corresponds to the energy needs, thus saving a lot of fuel and reducing undesired emissions.

Using the best operating point An additional advantage is the possibility to run the sets above the synchronous speed up to the maximum speed of the internal combustion engines. Thus, smaller sets can be installed, reducing space requirements and weight. In special cases there are, for instance, only three instead of four generating sets needed.

And the full speed range The higher the speed of the internal combustion engines and the electric machines, the better is their power density and power-to-weight ratio. That means, one can save a lot of space and weight using the highest possible speed as rated speed. This is of greatest importance for narrow engine rooms of several types of ships.


  • significant fuel savings
  • reducing emissions correspondingly
  • reducing running time
  • extending maintenance periods
  • saving operating costs
  • rapid answers on changing load demands

Fuel optimized power generation – a major increase of diesel-genset efficiency.

The start-stop function has become a common feature of automotive engines, saving fuel and reducing undesired emissions of the internal combustion engines. E-MS now has the solution for maritime applications.


Taking over this technology to operate diesel generating sets, the generator will be used as a motor to speed up the diesel engine instead of using the conventional starter equipment. Thus, one gets a powerful starter motor, wich is able to speed up the engine every time to any selected speed.

As the engine is pre-heated and pre-lubricated during a mission no excess-fuel is necessary to start the engine. Thus, there will be no smoke emission generated by this function. The injection process will be optimized by the engine management system to save fuel and reduce emissions.Having this in mind, generating sets should be shut off immediately if the power demand is low and can be taken over by other sets – even for a short period of time. If a sudden rise in power demand occurs, the engine will be started again automatically within a very short time compared with the procedure using the conventional starter system.  

As the diesel engines are designed for rapid load changes there are no limitations for frequent starts.

img-title-whiteIn addition to operating generating sets at variable speed, a start-stop-function – well known from automotive applications – can further optimize the onboard power plants and save even more fuel by switching off surplus generating sets and, as a result, operating the rest at higher effi ciency.