Internal combustion engines have minimum operating speed (RPMs), and
are most efficient, and develop the most torque, well above their
minimum speeds. In general, electric motors develop the most torque
at a stop, so they are ideal for driving a train's wheels, where you
have to start a huge mass moving from a dead stop.
Furthermore, motors can operate efficiently at quite a wide range of
speeds, far broader than an internal combustion engine.
If the drive on trains and ships always ran at one optimal speed,
direct drive from the engines might be the best. However, by having
the engine drive a generator, it CAN operate near its most efficient
speed most of the time. The loss of energy by going through a
generator and motor is easily made up by letting the engine run
at optimal speed and using a direct drive motor rather than gears
and clutches.
Jim
At 9 03 06, 02:58 AM, Stephen Humphreys wrote:
Just like train locomotives, the large diesel engines on these
ships drive generators, which in turn power electric motors, to
which are attached the propellers.
In just one sentence (because its off topic) can you, or anyone,
explain to a non-engineering type like me why the diesel engines
power the electric motors that power the means of propulsion rather
than cut the middle man out and have the diesel engine power the
means of propulsion?
Jim Elwell
[EMAIL PROTECTED]
801-466-8770
www.qsicorp.com
