OmCheeto said:
I don't remember anyone mentioning "alternators" while I was assigned to the surface fleet, and the submarine I was on had at least two things they called "motor-generators", MG's for short.
I can't speak for the specific MGs on the submarine, but I might be able to add some insight to the word "alternator."
The word
alternator is an archaic term that has somehow survived the test of time, but usually only when applied to the automotive field. Some terms that have not survived are
condenser which is now replaced by
capacitor, and
rheostat which is replaced by either
potentiometer or
variable resistor. For some reason,
alternator remains the most common term for an automobile's AC generator.
There is some history behind this. Some time ago (even a bit before my day), solid state rectifiers -- what we now call
diodes -- that were practical for high current, automotive applications, didn't exist. Vacuum tubes
could do it, but those aren't necessarily practical for a car engine. So the car's battery was recharged via an actual DC dynamo generator*. Dynamo generators have lots of problems such as being difficult to regulate and requiring more maintenance due to commutator wear. So in the 1960's, when silicon diodes became affordable, the automotive industry switched to using AC generators, a.k.a.
alternators, converting the AC signal to DC using the solid state silicon diodes. Getting rid of the problem prone, unreliable DC generators was a big deal. For awhile, having an
alternator was an indication (to the common person) that the car was designed with high-tech, state-of-the-art quality. I'm guessing that's why the name stuck.
But in other fields this apparatus is just called a generator. And if you want to get specific then it's an
AC generator (and if you want to get really specific it's a
synchronous machine or
synchronous AC generator). For example, the steam turbine at your local power plant is physically connected to and drives a really, really big version of your car's alternator. But they don't call it an alternator. They just call it a generator.
*(Dynamo generators are still used today on small engines -- like the one that powers your lawnmower. The principle involves a spinning magnet, typically attached to the flywheel [in small engines], that spins around, occasionally passing by a coil of wire. In combination with a capacitor (a.k.a
condenser) and a commutator a DC voltage source can be produced**.)
**(Edit: I should clarify that if your lawnmower is manually started, has no fancy-schmancy frills, and doesn't have an onboard battery, then there is no need for the additional components for DC conversion. In this case, the electrical system is called a
magneto system.)
?) somewhere in the picture.
