benefits of using ac or dc in cruise or navy vessels

[marinedummy]

i was wondering if anyone could tell me why ac is usualy the prefered generated type of electricity on cruise ships whereas on submarines dc power is used.

[SailDesign]

AC suffers less loss due to a lower current, and can use thinner wire. Also, on a cruise ship ,most passnegers will want to be able to plug in their hair-driers and such like.
On a submarine, the fequency of AC can give a clue to its location....

Steve "or something like that..."

[marinedummy]

thanks. does anyone know what type of motor ie; transverse flux, ac synchronous, dc motor, to generate the electricity in cruise ships?
i no the last reply said cruise ships use ac but dc can be converted in to ac. i just realy want to know what is the most efficient way of generating the electricity on any marine vessel anyone recommed a good website for information on this as well?

[SailDesign]

Dummy (sorry, that sounds bad)
ONe of the other reasons for having dc in subs is that you can't store AC. Batteries only come in DC. That said, it will be the only way to store electricity on a regular boat, and any inverter is just a loss waiting to happen. Stick with DC for boats.
Steve

[marinedummy]

what about advanced induction motors as they potentialy offer a higher torque per unit mass than already established technology?

is anyone aware if another company started to research transverse induction motors (TFM) after rolls royce stoped after withdrawel of funding from the mod?

also what about in say a naval vessel where dc is used for ship service distribution and ac for the propulsion bus bar, does a dc distribution medium exist that is not as expensive as and has a mass equal or lower mass to a ac distribution system?and therefore dc could be used to power the bus bar.

does equiptment exist that would not limit the power that could be transmitted by a dc system safely?

[SailDesign]

Unless you are using very high voltage DC, you will have to accept higher currents and thus higher weight for your bus bars. I'm sure there are problems with high-voltage DC apart from needing boosters to get it up the Empire State building (sorry - off topic), but I don't know them off-hand. Anyone?

Steve

[marinedummy]

technology at the moment limits the amount of power that could be transmitted safely by a dc system. however we are either close to or have just got to the stage where the equiptment exists that would make dc safe. also the swithching equiptment that is required is larger than ac.
also the usa IPS programme changed the functional defintion of one of thier modules fromsolid state circuit breaker to dc-dc converter when the use of equiptment became predominantly one of dc voltage conversion, nevertheless the circuit protection and fault current interuption of the module was retained.