THE ELECTRIC SHIPThe green chimney when starting a generator setNew New Solutions for Solutions forElectric Ship PropulsionElectric Ship PropulsionStart-stop function combined with variable generator speedBY HANS-JUERGEN REUSSor many years the start-stop of generating sets on board a given ves- bustion engines, as its electric or pneu- burg. With this system, synchronization function has become a com- sel, one of the gensets could be switched matic starting equipment is designed for of generators is no longer necessary. mon feature on automotive en- off and the remaining set or sets could only a relatively low number of starts. Thus, the E-PP together with the start-Fgines to reduce both fuel con- take on more load, creating far better ef- Thus it is impossible to use it for fre- stop function, as well developed by sumption and emissions. But the saving ? ciency. quent starts of the engines to save fuel. E-MS, is a combination with a potential potential is much larger with onboard The common practice of keeping all The second question concerns the time fuel-saving of up to 12%.electrical power supply and propulsion gensets running to be prepared for when needed from the signal to start the next systems. full power is needed again is neither genset to the point of taking over load by How it WorksLong-term measurements onboard economical or environmentally sound the generator. If the generators must be At ? rst, let’s take a look to the struc-passenger vessels with diesel-electric policy. synchronized, the chances to switch off ture and the operation of E-PP: The on-propulsion systems have shown interest- generating sets would be reduced. board installations consist of asynchro-ing insights into the load balance. The Managing the Load However, a proven technical solution nous generators, low-voltage inverters operational time with 30 to 40% load, The ? rst question now is how this can offers the E-PP – the electrical power and a common DC bus. The generators for instance, is much longer than that of be managed onboard the ship? There is pack – introduced several years ago by are excited load depending by assistance 70 to 80% load. no chance to make use of the standard the German specialist E-MS e-powered of inverters, providing constant volt-Depending on the size and the number starting equipment of the internal com- marine solutions GmbH & Co., in Ham- age at individual frequency. Keeping in 24 Maritime Reporter & Engineering News • OCTOBER 2014MR #10 (18-25).indd 24 MR #10 (18-25).indd 24 10/1/2014 9:37:14 AM10/1/2014 9:37:14 AM