If you have two identical motors (same HP) then having the same current "implies" that you have the same flow rate. Since you have two different horsepower ratings you may not be getting the same flow rate. The motor efficiencies and other design characteristics can be making the difference. As you regulate the media flow rate the motor responds by drawing the current required to accelerate the media.
If you lower the satellite table speed you will still get the same amount of coverage since you are exposing the part for the same amount of time (cycle time). Your questiong about getting the arc height is troublesome. Intensity is revealed only by running four or more strips for various exposure times and constucting a saturation curve. The curve is then interpreted using the 10% rule to determine intensity.
