Re: [CAD_CAM_EDM_DRO] How to select power supply???

Weyland wrote:

> Greetings All,
>
> I was recently able to bet some larger motors for the mill conversion,
> but am somewhat at a loss on how to correctly size a power supply for them.
>
> Do you choose the power supply first, or the driver boards?

Choose motors first (in general), then choose drivers that can
power the motor properly, then choose power supply to suit the
needs of the driver.

> Do you *add* all the amperages for *each* motor?

No. You need to make some sort of computation based on actual
power draw of the motors. Since almost all new drivers are swtiching type,
current into the driver is much less than current in the motor windings.
The current draw rises as motor speed increases. But, in general,
the drivers will rarely draw current equal to the rating of one winding,
assuming a sufficient DC supply voltage is chosen. Even if this
current is drawn, it will be for short bursts. Unregulated DC supplies
can supply peak power above the rating point for short periods.
Also, a slight dip in DC voltage will not affect the drivers.

>
> (for me adding three motors?)
> And how can I tell at what voltage these are safe to run at?
> 12V or 48V????? Or somewhere in between?

This is mostly determined by the specs of the drivers. Some can
handle no more than 35 V, some can go to 80 or so. The driver
limits winding current to whatever you set it to, so you don't really
need to worry about DC supply voltage versus the motor voltage
rating.

>
> I have *some* schematics available to me,
> but haven't been able to make heads or tails of them.
> Let me know what I should be looking for on them, maybe?

Schematics of what, motors, or drivers? Without comments on them,
a raw schematic may be of little use. You can't tell what voltage or
current it can handle just from the schematic, unless it says so in
words, without looking up the component ratings in databooks.

Jon