--- Begin Message ---
On Sat, 2007-09-08 at 09:27 -0400, Alfred Smart wrote:
> Hello Kirk
> Thanks for the reply
> 1.How about the VFD's can EMC control these directly to start and stop the
> spindle motor?
Yes, for most common VFD's. Generally, VFD's will have an analog speed
input, with 0 Volts being 0 RPM and 10 Volts being 100% RPM. Two digital
inputs control Forward and Reverse. Many of the controllers that are
compatible with EMC have analog outputs available.
VFD technology has changed quite a bit over time and features vary quite
a bit between manufacturers and models. You need to research the VFD you
plan to use. Some have an analog input with -10 Volts for 100% reverse
to +10 Volts for 100% forward. The new units tend to have data inputs
for control and monitoring, but (I believe) EMC is not set up to use
these yet.
(VFD input and output voltage, and phase rating varies between units
too, so you should watch this carefully. For my 240 Volt 3 phase VFD, I
use single phase 240 Volts, which has two legs, L1 and L2. My VFD is
expecting three legs, L1, L2 and L3. So, for the same output, the L1 and
L2 current will increase. Due to the two legs taking the load of three,
it has been suggested that the VFD should be sized larger than normal to
compensate. I believe the issue is much more complicated than that, and
depends on where the limiting factor in the system is. At the least, you
will need to make sure that your breaker and supply wiring can safely
supply the increased input (or basically the total system) current.)
> 2.The brake is 3 phase 230volt electro magnet release tied to the motor legs
> when the motor turns on the brake releases.
> I believe that the manufactured leg voltage drops from 185volt to something
> around 80-100volts at motor start up.
> That is why the idler motor seems to help.
I am not familiar with your particular brake, and of course you know
that working with these voltages can be very dangerous, and you should
get information from a number of sources, but... my guess is that your
brake uses mechanical tension of some sort to apply the braking force.
Then the electromagnet is used to overcome this tension to release the
brake. In this configuration, the electromagnet can use AC or DC of the
appropriate voltage. You could get rid of the third leg dip by running
each leg into a diode bridge and a capacitor to create DC. One problem
that comes to mind with this, is that when you first apply power, the
motor will what to start turning and the DC supply may still be coming
up to voltage. You could use a motor delay relay to fix this but now
things start to get complicated.
You may be better off posting your question on a list where your problem
has already been addressed. Two come to mind:
http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi
and
http://www.cnczone.com/
And/or you may try to optimize the performance of your converter using
this information:
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
Also, you may want to check that your supply wiring is the proper size
and all connections are tight and not hot while under power (be
careful).
I hope this helps.
Kirk Wallace
>
> ----- Original Message -----
> From: Kirk Wallace <[EMAIL PROTECTED]>
> To: Enhanced Machine Controller (EMC) <[email protected]>;
> Alfred Smart <[EMAIL PROTECTED]>
> Sent: Friday, September 07, 2007 3:32 PM
> Subject: Re: [Emc-users] Non EMC? for the Electrical Genius's
>
>
> > I may be off base here, but here is my two cent's worth.
> >
> > My Hardinge HNC came with a Warner electric release brake. It uses a
> > permanent magnet to activate the brake while the power is off. To
... snip to end
--- End Message ---
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
