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VFD wireing for cincinnati mill with mag starter

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gaston

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#1
IM BACK!!
I got great help and handholding from Jim Dawson with my last VFD wireing ,( clausung lathe), so here I am again with a new (to me) machine and another VFD problem.
How do I wire a 3 phase machine with mag starters to a VFD ??
As I stated last time Im a retired bodyman and I don't know stink about wireing. and to make it a bit harder, I had a minor stroke and some of my memory got screwed up so I don't figure things out as well any more.
Do I wire around the starter and direct to the motor or?? also I can't find any wireing information on this machine beyond chasing wires
thanks Gaston
 

RandyWilson

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#2
Yes, you go around the starters. The Cinci wiring is a work of art, but it must be disabled. What type of mill, and does it have an power feeds?
 

gaston

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Yes, you go around the starters. The Cinci wiring is a work of art, but it must be disabled. What type of mill, and does it have an power feeds?
its a 2m horizonal and I think it is power feed on all three (XYZ) axis It seems to be mechanical thru gears
 

Ulma Doctor

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#4
Hi Gaston,
you'll need to make a decision,
whether to power the mill with a rotary phase converter or a VFD
VFD's don't play nice with magnetic starters
VFD's don't play nice with multiple motors turning off and on, with a single drive-
(multiple VFD's would be necessary if you were to do it by the book of Hoyle)

for your situation, i'd consider a RPC to power the mill.
it would require the use of an idler motor @ 1.5X the capacity of the largest motor it is trying to start.

for example the mill had a 5hp main drive motor,
a 7.5hp RPC would be sufficient to operate all the functions of the mill simultaneously ,
provided the idler was up to speed before the multiple functions are employed.

i'm not suggesting that you can't hook a single VFD to drive the entire mill's operation but i wouldn't recommend it for a couple of reasons:
1-cost, you'll need a VFD to cover the total input needs of ALL the motors simultaniously
all the motors would have to be used at the same frequency, there would not be individual frequency control without a lot of brainstorming
that drive will cost in excess of 500 unless you get a deal somewhere.
2: reliability.
when you do something to a VFD that's not necessarily by the book, you take the life of the drive into your hands
generally when we stress the drive, you can expect a shorter lifespan.
you just hope the lifespan exceeds the work to be completed.

a RPC, would be my recommendation for longevity and simplicity.
you can make one yourself with some will, some skill and some money.
there are many ways to do it,
but here is how i do it...
http://www.hobby-machinist.com/threads/rpc-simple-design-unbalanced.12712/

good luck, however you decide to go!
i'm happy to help out if you need any type of assistance
 
Last edited:

RandyWilson

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#5
Unlike other machines, Cinci table drive motors are always on. The table movement is controlled by clutches and transmissions, not motor speed. With that in mind, I saw two options for my 1B vertical. I could use an RPC and treat it as line power. Or I could use a VFD to drive both motors, and just not turn the table motor on/off with the VFD on. If using the table drive and feed rate was critical, I set the VFD to 60hz and use the belts to change spindle speed. Without the table on, I use the VFD and "back-gear" for speed control. With a RPC, I would be locked to 60hz always, and be constantly changing belt positions.
 
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