Re: [CAD_CAM_EDM_DRO] Re: Power Supply Caps and Xformer

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.
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!

>What type of capacitors are best?
>
>

Aluminum electrolytics will be the only thing you can find in the right
voltage/capacitance range, anyway.

Jon