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Hi! This is Phil Ranger from Lab-Volt.
Today I want to do a quick simulation of an elevator system.
The main difference when you're using an elevator is that
because of the counter weight and the fact that people are moving in and out
of the elevator
sometimes you will have a torque that will be in the same direction of the
direction you want to move,
in which case you might want to supply either less power to your motor,
or have a negative
power out of your motor to
slow down your load, and sometimes you need to provide,
as in the regular case, acceleration to go in the same direction of your motor.
To do that I am the Lab-Volt four-quadrant dynamometer
to adjust the torque on that system. And I will show you
how I do that right now.
So here I want to go,
not only for break, or for prime mover,
but I want to go to a constant torque
source. So in that case here
I have, for example, my
positive constant torque
prime mover break. I set it up to
the torque that will be high enough to have
movement in my system. So when I press Start I will see that my
motor, or my elevator, starts moving right away.
I can slow my elevator by applying power
on my motor, up to a point where it would completely stop,
or go in the opposite direction. But this is not
best system because
I am always using this as a motor. You'll want to be able to recoup that
energy
so you could use your motor as a generator in that case.
If I go to a negative torque here, I will see that
my speed will change direction,
so here when I press Start, I start moving in the other direction,
and in that case, even if I tried to increase
the power I'm sending to the motor, there's nothing I can do about it. I can
only
accelerate my system.
What I could do is to exchange the connection
polarity on my motor and then
I'm able to provide a slowing torque, a counter torque to that system.
Up to a zero speed points or in
the opposite direction.
Of course you don't always want to send energy to the motor
to slow it down, so there is always a magnetic brake that you can add on the
system.