Re: Confused over My own Calculations!

OK. This is very simple.

1. If there is a current rating on the motor then it is almost
invariably the unipolar rating.

2. Series (8-wire) = Full-winding (6-wire). Use 1/2 the rated current.

3. Parallel (8-wire) = Half-winding (6-wire). Use the rated current.

4. Four-wire motors; use the rated current.

The power supply current draw from your power supply will be much
less than the motor's rated current. This is because your power
supply voltage is much higher than the motor's rated voltage. Power
is Amps times Volts as Jon correctly points out.

The 2/3 business is also very simple. The motor takes a certain
amount of power just to turn over with no load applied. As you apply
load (that is what the motor is there for after all), it requires
additional power from your power supply up and above what it needs at
no load. This is good, it gets converted into mechanical energy.

At some point the load is just short of stalling the motor.
Empirically the current drawn from the supply just happens to be 2/3
of the motor's rated phase current. This is from data I have taken
from many, many "round" motors.

The new "square" motors are better and more efficient. Preliminary
data shows they can draw current equal to or more than the rated
phase current. This is a very good thing; it means more electrical
power gets converted to mechanical power. As soon as I have enough
data to draw firm conclusions, I will be posting new guidelines for
them regarding power supply current draw.

Mariss

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> mayfieldtm wrote:
>
> >
> > Thanks Jon:
> >
> > I feel much better now.
> >
> > So where does that "2/3" factor I keep seeing come from?
> > Or is that one of those good ol empirical rule of thumbs?
>
> I gather its an empirical rule.
>
> > And that pesky Name Plate Amper Spec.
> > Is that a max. per winding or some total?
>
> The nameplate rating is the max. per winding, which is also the
nominal current
> for full rated torque. But, an 8-wire motor complicates the
situation.
> The nameplate rating is for unipolar or bipolar series connection.
> You double the current when using the windings in parallel.
>
> >
> > And the Gecko drive amper setting should be set to this value for
> > series (8 wire motor) and twice this value for parallel?
>
> Yes.
>
> Jon