RE: [CAD_CAM_EDM_DRO] Re: QUESTION ABOUT SERIES OR PARALLEL ON STEPPER MOTORS - ref post 52721

Thanks for all the input. This is really helping out.
A gentleman in New Zealand (thanks Neil) was kind enough to help identify
the stepper motor I apparently have (at least physically it's the same size
and appearance) and dividing the rated voltage by the current gives me about
the same resistance I measured on my unmarked motor (calculated from his
nameplate values: .23 ohm, my measured value about .29 ohm - I do not know
if the difference is significant and means that the two motors are in fact
different).

The nameplate on his motor rates it at 2.1 volts and 9.2 amperes.

Is it OK to drive this at 62 volts DC? I read that the voltage should not
exceed 25 times the rated voltage which would be 52.5 volts.

Since the application is a direct connection to the XY and Z axis of a
Bridgeport Milling machine, (and since the drive tops out at 8 amperes) is
it better to try running it at 8 amperes in parallel or at 4.5 amperes in
series?

Again, thanks much for all your help.

Jeff


-----Original Message-----
From: Nigel Bailey [mailto:nigel.bailey@...]
Sent: Friday, February 14, 2003 10:37 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: RE: [CAD_CAM_EDM_DRO] Re: QUESTION ABOUT SERIES OR PARALLEL ON
STEPPER MOTORS - ref post 52721


Thank you Mariss,
Took a minute or two to digest, but yes I agree! nice to be set thinking.
Nig.

-----Original Message-----
From: Mariss Freimanis <mariss92705@...>
[mailto:mariss92705@...]
Sent: Thursday, February 13, 2003 6:07 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: QUESTION ABOUT SERIES OR PARALLEL ON STEPPER
MOTORS - ref post 52721


Nigel,

Close but not on the nose.

Parallel nductance is 1/4 of series inductance but the improvement is only
2-fold, not 4-fold. Here's why:

Properly stated, torque is proportional to "ampere-turns", not just current.
Though the inductance is 4 times smaller, the current has to be twice as
high, making the advantage 2:1 over a series winding.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Nigel Bailey" <nigel.bailey@o...>
wrote:

As I said at the top, stepper torque is proportional to

> current, so limit on torque will be reached at a much higher speed,
> (theoretically 4X faster) for a parallel connected pair than series.
>
> Whilst on this subject, this is the reason why current controlled

drivers

> are used with supplies at a much higher voltage than the steppers

are DC

> rated at. The high voltage is there to force the current in the coil
> (inductor) to rise more quickly, up to it's limit, but in this case

it's

> limit is controlled by the current controlling driver, rather than

the

> stepper motor coil's DC resistance.
>
> Has that confused anyone further?
> Nig