Re: [CAD_CAM_EDM_DRO] Clarifications needed -

On Friday 12 September 2003 10:55 pm, Tim Goldstein spake:

> > What causes them to get hot? (just curious)
>
> Rapidly discharging and recharging the cap causes it to heat. If you are
> using a large motor and you have either long wires from the power supply
> or a fuse in the line then the onboard cap will be discharged when the
> coils are energized (20 kHz chop I think) as sufficient current can not
> be supplied by the incoming power lines so the cap provides the current.
> Putting another cap at the terminals of the drive will help share the
> load so to speak and reduce the heating.

Ah, okay. Thanks for that explanation.
So this would be the "flywheeling" thing.
While the power wires are short, I do have fuses in line,
so I'll go to RadioShack and buy some caps tomorrow.

> > I always get confused here, so I'll ask what the majority
> > common practice is -
> > Use the ground of the parallel port, or +5V
> > off of one of the computer power supply leads?

> Gecko G201 must use +5. G210s allow you to pick. The parallel port can
> do a better job if it is sinking the current and you are sourcing from a
> +5 v line.

Okay, thanks. I'll pick off from one of the power cables.

> > Another good point. I'll hafta look into what the UPS's rating are.
>
> To me plugging in the motor power supply is like putting a laser printer
> on a UPS. If I remember you are a systems admin?

For only a short while longer.
I can't stand it anymore, and having opened up my own shop, have
been *MUCH* more happier than I've been since getting into SysAdmin.
The SysAdmin thing was a fluke, having been a Toolmaker originally.
I'm happiest when I'm making something metal.

> If so I am sure you
> have seen the result when this happens. Quick way to reduce even a large
> UPS to trash. I have never tried it with a CNC power supply though.

Yeah... I've seen it. And you're right.
Didn't occur to me to connect the dots.

Looka like I have an answer.

Thanks again~!

Best,

Weyland