Re: Motor calculations? Help!

That is correct the 120V is what comes out of the secondaries. THe
input can be set for many different inputs, but is currently set for
220V 3 phase. I pretty much forgot about the idea of using the three
phase transformer. From what I read it could work, but we be derated
to 1/3 which would be too wimpy. Whover said get a 220:120 step down
rated at 2.5 KVA pretty much hit the nail on the head. 2.5 KVA is
the original transformer value. I don't really need 120 on the
secondary though, it would be nicer if it was about 90.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "spc_aux" <aux34@s...> wrote:
>
> I believe he is referring to the secondaries of the transformer
when
> he indicates 120v. Presumably the primaries are for 208/220/440 or
> similar.
>
> Pete C.
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...>
wrote:
> > Lance Hopper wrote:
> >
> > >Hello,
> > > I've been talking to the guy myself trying to help him out.
> He's
> > >already bought 200V 40A Rutex drives as I understand. Now he's
> > >trying to figure out the PS.
> > >
> > >
> > Ah, OK, that sounds like the best course.
> >
> > > The original drives were fed 120 3ph from the secondaries of
a
> > >2.5kva 3ph transformer as he describes via his electrical
> schematics.
> > >He was trying to see if the stock 3ph transformer (has delta
and Y
> > >wiring configurations, he has the schematics, maybe he should
> post)
> > >could take ~220 1ph (all he has available) and output ~120 1ph
> that
> > >could be rectified and used for the Rutex drives. I doubted
that
> it
> > >would work and be dangerous/stupid to try, but what do I know.
> > >
> > >
> > Is there any way to use a 3ph transformer for 1ph in and 1ph
> out?
> >
> > No, it really will not work well on single phase. Where did
this
> thing get
> > 120 V 3-phase power? That is an extremely odd voltage. 208 and
> 230 V
> > L-L is the most common low-voltage 3-phase supply in the US.
Or,
> is this
> > 120 V line-neutral voltage? That would normally be termed 208 V
3-
> phase,
> > as the line-line voltage is how it is usually measured.
> >
> > > Is there any way to use a 3ph transformer for 1ph in and 1ph
> out?
> > >What if he used a phase converter and ran 220 3ph to the
primary,
> > >then just ditched one of the 120 3ph legs to get 120 1ph to be
> > >rectified/filtered for the Rutex drives? Any safe/smart
> workarounds
> > >on this?
> > >
> > The best way to go, I think, would be to use a 240:120 V step-
down
> > transformer
> > rated for 2.5 KVA at that voltage. (If you can't find one with
> that
> > exact rating,
> > you could use a 480:240 V 5 KVA transformer at half input
voltage.)
> > With a 240 V output with a center tap, and using 2 diodes, you
can
> get
> > 170 V DC, which may be acceptable to the Rutex drives. (I'm
being
> cautious
> > here, because the Rutex's 200 V rating is apparently the actual
> rated
> > voltage
> > of the transistors. So, I don't know if the 200 V Rutex drive
can
> > actually be
> > run off 170 V DC without problems. It is probably best to ask
> Rutex about
> > that. If necessary, one can get tapped autotransformers to
adjust
> the
> > voltage down somewhat.
> >
> > Jon
> >
> > >
> > > Otherwise, he's going to have some $ into some large kva
> > >transformers for the X/Y and Z servos.
> > >
> > >--- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnc_4_me"
<cnc4me@g...>
> > >wrote:
> > >
> > >
> > >>--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...>
> > >>
> > >>
> > >wrote:
> > >
> > >
> > >>>cnc_4_me wrote:
> > >>>
> > >>>
> > >>>
> > >>>>Jon, I do not see this the same way you do. Don't you think
> the
> > >>>>continuous current rating is more important than the peak
> > >>>>
> > >>>>
> > >current
> > >
> > >
> > >>>>rating? 28 Kg-Cm / 2.44 Kg-Cm/Amp = 11.5 amps, a gecko
would
> > >>>>
> > >>>>
> > >>still
> > >>
> > >>
> > >>>>have plenty of reserve. 20 amp limit would still give 49 Kg-
Cm.
> > >>>>
> > >>>>
> > >I
> > >
> > >
> > >>>>wish i had one of these motors for my Z axis.
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>What's the peak rating for, if you never can get closer than
20%
> > >>>
> > >>>
> > >of
> > >
> > >
> > >>it?
> > >>
> > >>
> > >>>I might be worried that you might not be able to break static
> > >>>
> > >>>
> > >>friction on
> > >>
> > >>
> > >>>the table with 20 A. What is the leadscrew pitch, and is the
> > >>>
> > >>>
> > >screw
> > >
> > >
> > >>directly
> > >>
> > >>
> > >>>driven by the motor, or is there a belt reduction?
> > >>>
> > >>>What horsepower and spindle taper does the machine have?
> > >>>
> > >>>Jon
> > >>>
> > >>>
> > >>From what I understand from reading these forums is that any
> force
> > >>much greater than continuous rating isn't to usable, maybe for
a
> > >>fraction of a second for fast acceleration. Maybe if he
adjusts
> > >>acceleration so it does not snap your eyeballs it would be ok.
> > >>
> > >>49 Kg-Cm is about 47 lb-in. Nothing to sneeze at.
> > >>
> > >>
> > >>I guess what I am getting at is I would not try to discourage
> this
> > >>guy and say it will not work. I think it is very likely it
will
> > >>work with slower acceleration and with 30% less speed on X and
Y
> > >>because of voltage restrictions with Gecko drives. Rutex
would
> > >>
> > >>
> > >give
> > >
> > >
> > >>him full speed and slightly higher acceleration.
> > >>
> > >>
> > >>Wally
> > >>
> > >>
> > >
> > >
> > >
> > >
> > >
> > >Addresses:
> > >FAQ: http://www.ktmarketing.com/faq.html
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