Re: SCR DC Motor Controllers... Need Advice.

Mark,

This is best understood by drawing a graph. Make the +Y axis RPM. Put
a point on the axis at 1". Make the +X axis torque. Put a point on
the axis at 1" as well.

Connect the 2 points. That is the motor load-line.

Now draw a horizontal line starting from 0.1" on the +Y axis. Draw
another horizontal line staring from 0.9" on the +Y axis.

The line starting from 0.1" is the speed-torque curve when the speed
control is set to 10% of full speed. Note how you can increase torque
load to 90% of stall before the speed begins to drop.

The line starting from 0.9" is the speed-torque curve when the speed
control is set to 90% of full speed. Note how you can increase torque
load to only 10% of stall before the speed begins to drop.

Those are the results you will get.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "mmurray701" <gmurray@n...>
wrote:

> I need some advice about SCR drives. I need to know if they provide
> constant torque at all speeds. For example if the controller is
> set to half speed, is the torque also reduced to half or does it
> remain constant? And finally, will there be any difference in
> performance in a motor running from a 90v SCR drive set at full
> speed, and a motor wired directly to a 90v source? Thanks in

advance!

>
> Mark