Re: [CAD_CAM_EDM_DRO] Now have possession of my mill

On Thursday 26 August 2004 00:52, Dennis Cartier wrote:
> The machine currently has an 'Inland Motor, AC Spindle servo unit' that
> takes 0-10V signal along with a spindle enable and direction signal to
> control the RPM and rotation of the spindle. It would be nice to keep
> this and somehow interface it to EMC, I am just not sure if I can.

Good news, EMC will support spindle speed control as long as you have a spare
analogue output available on the interface. I would suggest keeping the
existing servo amps if they use standard +/- 10V control unless they are
really vintage.. Perhaps replacing them with Copley sometime in the future
would be an option (On a side note, www.weirdstuff.com have some Copley amps
at $150).

> I am bit confused on 1 point. The machine was operated on 480V 3P and I
> want to use 230 3P, and the specs for the spindle controller show either
>   230 or 480 input, then a power transformer with the controller
> delivering 220V to the spindle motor. What is the point of providing
> 480V if the motor only needs 220V?

Supply current would be the reason - At 480V the current draw will be half of
that at 230V so the power cables in the street can be much smaller.
This may not apply to your area, but in the UK most streets have a single
415V 3P running the full length. Each house is supplied from Neutral and one
leg of the 3 phase cable to give 240V at the meter - The power company will
group each dwelling and try to balance the load across all three phases and
so avoid having to lay in heavy cables.


Regards, Paul.

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