Re: 8-wire stepper: series is 1/2 the amps.Strange but True

Jeff,
Good point, the resistance will add, but now I'm going to have to
look into it more. Series inductances add linearly , but I'm
assuming this is only if the magnetic fields arent close enough to
interact.

Using the eq. L =( N^2 * uA)/(length of windings across core)
where u(perm) and A(Area) are the same for both coils

would indicate that the inductance goes up as a square of turns, but
also is reduced by a factor of 2 as the lenght of the core doubles
in adding the second 1/2 of the coil.

I'm getting confused now :-)

-Lee





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "jeffalanp" <xylotex@h...>
wrote:

>
> Hi Lee,
> Won't series winding (full winding) RESISTANCE be TWICE the

amount

> of the single coil (1/2 coil), while your series winding

INDUCTANCE

> be FOUR times that of the single coil (1/2 coil)?
>
> With series winding (full winding), you have twice the number of
> turns of wire being energized as half winding, so you use half the
> amount of current to acheive the same holding torque.
>
> Jeff
> http://www.xylotex.com
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lee Studley"
> <indigo_red@q...> wrote:
> > Hi,
> > I would in my early days have agreed until Mariss gave me new
> > insights into motor inductance:
> >
> > When wiring stepper coils in series, or full winding, the

amperage

> > is 1/2 the plate rated( I think this plate rating is for a

single

> > coil energized), this is due to the inductance being twice the
> > amount than that of a single or 1/2 coil. Using V=L di/dt and

stick

> > a fixed dt=1 (1sec) relation in there to simplify the thought
> > process, and setting V equal to the fixed motor drive voltage.
> > V is proportional to L * di where di is a change in current. So

if

> > you double the L value( 2coil in series) then di ( or I) had to
> > decrease by 1/2 if V is fixed. This relation shows the ability

of

> an
> > inductor to oppose a change in current.
> >
> > So 1 amp full series, or 2amp single or 1/2 coil.
> > Do the experts agree?
> > -Lee
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "forumtvm"

<forumtvm@y...>

> > wrote:
> > > "WUKSTA" <gerry@z...> wrote:
> > >
> > > > After reading all the posts on this subject I am a little
> > > confused.
> > > > I have three Vexta (Oriental Motor) PK268M-02A steppers that
> > will be
> > > > driven by Gecko 201 drives. These steppers are 187 in/oz.;
> > 2A/phase;
> > > > 4.5V; 2.25 ohms/phase; .9 deg; 6 wire motors. If I run these
> > motors
> > > > "Half Coil" would I run them @ 2amps or 4amps? With my cheap
> volt
> > > > meter, I get a resistance of 4.8 ohms full coil & 2.5 ohms

half

> > > coil.
> > > >
> > > Hi Gerry,
> > >
> > > I believe it should be 2Amp. Your cheap voltmeter I believe

has

> > > confirmed that - 4.5V / 2.5 ohm = ~2A
> > >
> > > Peter