CAD CAM EDM DRO - Yahoo Group Archive

Re: Power Supply Caps and Xformer

Posted by Tim Leech
on 2004-09-02 00:45:38 UTC
--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
> Abby Katt wrote:
>
> >Les, Hi
> >
> >This is going to be for Servo drives, like the nice big (the
biggest
> >ones) motors Dan Mauch has on his website.
> >
> >I knew about the voltage formula, so that one is easy. But thanks.
:)
> >
> >
> Ah, then, you definitely are oversizing it! I'm assuming you are
> talking about the
> 600 Oz-In Ametek motors. You should know that at standstill, with
> 50 V across these motors, you can just get 12 A through them. When
they
> are moving, the back-EMF generated by the motor reduces the maximum
> current. At 900 RPM the back-EMF is 36 V, so you can only get
(50-36)/4
> = 3.5
> A through the motor. What this all means is that it is IMPOSSIBLE
for the
> Gecko drive to EVER draw 12 A from the power supply, even for an
instant.

Excuse my ignorance (I've never dealt with servo drives), but why is
it impossible? I appreciate the back emf bit, but what about stall or
starting conditions?


> You can figure out the curve, but it works out that the highest
peak
current
> will be no more than 6 A or so per axis. Also, these motors are
rated at
> 12 A PEAK, but something like 4 A continuous. So, the continuous
draw
> must be less than 2 A from the power supply. For a 3 axis system, a
> 6 A power supply would never even use the reserve capacity. A 3 A
power
> supply would likely be adequate for a mill, and 4-5 A for a router!
>

Again, why only 2A when the rating is 4A continuous?
I must be missing something, I used to know a bit about electricity
but, as I've said, I'm ignorant when it comes to servo motors.

Cheers
Tim

Discussion Thread

Abby Katt 2004-09-01 02:08:06 UTC Power Supply Caps and Xformer Leslie Watts 2004-09-01 06:09:48 UTC RE: [CAD_CAM_EDM_DRO] Power Supply Caps and Xformer Abby Katt 2004-09-01 06:20:48 UTC Re: Power Supply Caps and Xformer Leslie Watts 2004-09-01 06:53:30 UTC RE: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer Jon Elson 2004-09-01 07:41:24 UTC Re: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer JanRwl@A... 2004-09-01 08:47:24 UTC Re: [CAD_CAM_EDM_DRO] Power Supply Caps and Xformer Jon Elson 2004-09-01 12:17:03 UTC Re: [CAD_CAM_EDM_DRO] Power Supply Caps and Xformer kmslinda 2004-09-01 15:33:47 UTC Re: Power Supply Caps and Xformer Andy Wander 2004-09-01 16:10:18 UTC RE: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer Fred Smith 2004-09-01 16:27:25 UTC Re: Power Supply Caps and Xformer sargossa_99 2004-09-01 17:05:36 UTC Re: Power Supply Caps and Xformer Greg Jackson 2004-09-01 19:09:35 UTC RE: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer Jon Elson 2004-09-01 20:57:11 UTC Re: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer Tim Leech 2004-09-02 00:45:38 UTC Re: Power Supply Caps and Xformer Abby Katt 2004-09-02 02:33:47 UTC Re: Power Supply Caps and Xformer Rod McBeath 2004-09-02 06:43:39 UTC RE: Re: Power Supply Caps and Xformer Jon Elson 2004-09-02 10:40:38 UTC Re: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer Jon Elson 2004-09-02 10:46:12 UTC Re: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer