Page 27: of Marine News Magazine (March 2018)

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mal range of a mechanical drive system. the switchboards. The DC current is DC based propulsion systems provide

Under the umbrella of diesel elec- then inverted back as necessary to pro- the most bene? t when combined with tric propulsion, there are several vari- vide AC power to the propulsion and some type of energy storage where the ants that exist on the market today: hotel loads. Direct Current systems DC grid can allow the batteries to are smaller and lighter in general, with provide instant power response to the

YBRID

H (PTO/PTI) fewer parts inside the switchboards. ship’s electrical system.

Hybrid systems make use of a me- chanical shaft line with a power take off and power take in (PTO/PTI), combined with an electrical generation system. This system combines the ben- e? t of direct drive propulsion through a gear box with the ? exibility of a ‘power boost’ from the ship’s electrical system, but also allows for the main en- gines to run more ef? ciently by provid- ing electrical power to the ship when the power is not needed for propulsion purposes. When more power is needed, the generators act as motors supplying additional power to the shafts via the

PTO/PTI. During lower power opera- tion, the main engines can be clutched out and the vessel can operate on the electrical motor alone, or the main en- gines can supply propulsion power and also power the PTO/PTI for supply of electrical power for auxiliary loads.

YSTEM

A/C S

The A/C diesel electric system is the most traditional and common diesel electric system on the water today. It consists of an electric power plant with several generators providing power for all of the loads on the vessel; propul- sion, auxiliary, and hotel. Power from the switchboard is provided to the pro- pulsion motors via variable frequency drives in order to allow the motors to operate at virtually any shaft RPM.

YSTEM

D/C S

The D/C diesel electric system is very similar to the A/C system but provides some improvements in cer- tain areas. The AC current from the generator is recti? ed to DC at the gen- erator and distributed directly through www.marinelink.com MN 27

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