[sdiy] OT: Generator?

[Magnus Danielson]

From: KA4HJH <ka4hjh at gte.net>
Subject: Re: [sdiy] OT: Generator?
Date: Thu, 26 Apr 2001 04:08:43 -0400

> Yeah we're really milking this (off) topic now, but I know we've got some
> railfans on this list...and I never did get that Lionel train set for Xmas.
> 8^(

Why don't you say it? This have gone way of tracks... or was it onto them?

> >an electric motor provides  tremendous torque from a
> >dead stop. It wants to turn in a big way when power is applied, or it will
> >dissipate the energy as heat.
> 
> Produces the most torque when it's stalled, doesn't it?

Actually, it depends on the motor type. It is interesting to plot the
torque as a function of the RPM.

> >Piston driven motors physically can't run when
> >they're not turning, so there's no torque available. They have to be running
> >at some higher speed to generate torque. That's the main reason the
> >horsepower of a diesel is converted to electricity for electric motor torque
> >in locomotives. You need torque to pull the tremendous weights, and you need
> >it from standstill.
> 
> Exactly. I seem to recall that you test the power of a motor by braking it
> to a halt. With an ICE motor the torque peaks somewhere right before it
> stalls.
> 
> Piston-driven steam engines didn't have this problem since they were
> ECE.

Steam engine cars is claimed to have better acceleration than their
more normal sport cars. There where some company in NY that makes
them, but I don't know any details. Anyone that could fill in the blanks?

> >Notice when you hear a diesel train engine, it's rumbling
> >at about the same RPM all the time? That's horsepower available to generate
> >current for electric motors, regardless of train motion. The diesel generator
> >eliminates the need for the overhead lines (or powered rails in a subway
> >engine).
> 
> They actually have a surprisingly limited speed range. A typical locomotive
> these days is over 4000 horsepower thanks to all the high tech gadgetry.
> 
> Steel wheels on steel rails have the highest adhesion when they're just
> slightly slipping so modern locomotives use computers to keep the wheels
> slipping just the right amount. They use doppler radar to measure the
> ground speed and compare it to the rate of rotation of the wheels. You can
> almost triple the tractive effort this way!

Ah, interesting!

Things that you can pick up on this list is amazing! ;)

Cheers,
Magnus