> David, your reply would slow the motor down as it wouldn't be getting enough
> power. Or I have bitten hook, line and sinker! ;-)
I said "put resistors across the traction motor" ie, in parallel with the
armature. Of course, you would disconnect the supply first, or you would be
wasting your time.
When operating normally, motors convert electrical energy into kinetic energy and
heat energy. When you turn that same motor into a generator, you are converting
kinetic energy into electrical energy and heat energy. By placing resistors
across the generator, you are converting nearly all of the electrical energy into
heat energy. As energy can neither be created or destroyed, the more heat that is
dissipated, the higher the retarding effect of the generator due to the fact that
the kinetic energy (motion) is turned into heat energy.
I am not even going to mention regenerative braking, as that was not asked about,
but to confuse matters a bit, when there are no down trains in the same electrical
section on the Blue Mountains, up trains are actually using dynamic brakes. The
resistoras are located at the substations in green boxes with many vents on the
sides. Tangaras are fitted with dynamic braking grids. They, like the substation
dynamic resistors, are set to be enabled when the overhead voltage gets to 1750
Volts.
Does this make sense to anyone else?
-- David Johnson CityRail Guard trainman@ozemail.com.au http://www.ozemail.com.au/~trainman/