How to set up VFD to properly control KBC bench mill.

Home| Search | About
User Password
Register Now! Lost Password?

General Metalworking - All aspects of working with metal. 

Bookmark this page:  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
How to set up VFD to properly control KBC bench mill. Vernon 10-06-2008
Posted by Vernon on October 6, 2008, 1:08 pm
Please log in for more thread options

Gentlemen,

I bought a Hitachi SJ200-022NFU2 model, 3 HP VFD to control my "new"
mill, which has a 2HP 3 phase motor.

This model, a "constant torque" VFD, is versatile and sophisticated,
and contains control options far beyond my needs and expertise.

I have carefully and almost completely read the owner's manual. The
basic installation is simple enough. You bring in the 2 legs of 220V
single phase from a 30 amp fuse or breaker, and connect these to
inputs 1 and 3. You ground the mounted VFD and the mill motor in a
star pattern. You connect the appropriate 3 outputs from the VFD to
the motor.

You go through an initial programming sequence, setting up certain
basic parameters. You power up the VFD. You verify certain that
certain pre-conditions are met and that certain LEDs are on or off on
the keypad. You take a deep breath, make the sign of the cross, and
press START.

After that the going gets sort of tough. Here are a couple of things
I don't understand. I will humbly accept your guidance.

First, it is my understanding that it is possibly fatal to the VFD to
switch the motor on or off from the mill's own on-off switch, or to
otherwise control the mill (instant reverse for example) EXCEPT
through the VFD's programmable circuits.

This leads to the following questions:

1) Do I remove the mill's on-off switch completely or otherwise wire
it permanently in the ON position?
2) Do I similarly wire around the wires going to and from the mill's
FORWARD - REVERSE toggle switch and re-route these wires to the VFD's
programmable inputs/outputs?

There was previously some discussion here about whether a VFD can
adequately handle the mill's instant reverse. However, upon careful
reading of the manual the VFD does seem to have a programmable "node"
that allows for this. Apparently this can be tweaked a couple of
ways. One of these involves installing additional resistors. Another
SEEMS to provide for programming the injection of a DC current into
the motor to stop it from coasting. I think these two things are
related but I'm not sure.

I think I can get the thing installed this weekend so that it will at
least start and run. However, my brain is a lot murkier as regards
these programmable controls.

Thanks to one and all.

Vernon

Posted by Tim Wescott on October 6, 2008, 1:36 pm
Please log in for more thread options

Vernon wrote:
> Gentlemen,
>
> I bought a Hitachi SJ200-022NFU2 model, 3 HP VFD to control my "new"
> mill, which has a 2HP 3 phase motor.
>
> This model, a "constant torque" VFD, is versatile and sophisticated,
> and contains control options far beyond my needs and expertise.
>
> I have carefully and almost completely read the owner's manual. The
> basic installation is simple enough. You bring in the 2 legs of 220V
> single phase from a 30 amp fuse or breaker, and connect these to
> inputs 1 and 3. You ground the mounted VFD and the mill motor in a
> star pattern. You connect the appropriate 3 outputs from the VFD to
> the motor.
>
> You go through an initial programming sequence, setting up certain
> basic parameters. You power up the VFD. You verify certain that
> certain pre-conditions are met and that certain LEDs are on or off on
> the keypad. You take a deep breath, make the sign of the cross, and
> press START.
>
> After that the going gets sort of tough. Here are a couple of things
> I don't understand. I will humbly accept your guidance.
>
> First, it is my understanding that it is possibly fatal to the VFD to
> switch the motor on or off from the mill's own on-off switch, or to
> otherwise control the mill (instant reverse for example) EXCEPT
> through the VFD's programmable circuits.
>
> This leads to the following questions:
>
> 1) Do I remove the mill's on-off switch completely or otherwise wire
> it permanently in the ON position?
> 2) Do I similarly wire around the wires going to and from the mill's
> FORWARD - REVERSE toggle switch and re-route these wires to the VFD's
> programmable inputs/outputs?
>
> There was previously some discussion here about whether a VFD can
> adequately handle the mill's instant reverse. However, upon careful
> reading of the manual the VFD does seem to have a programmable "node"
> that allows for this. Apparently this can be tweaked a couple of
> ways. One of these involves installing additional resistors. Another
> SEEMS to provide for programming the injection of a DC current into
> the motor to stop it from coasting. I think these two things are
> related but I'm not sure.
>
> I think I can get the thing installed this weekend so that it will at
> least start and run. However, my brain is a lot murkier as regards
> these programmable controls.
>
> Thanks to one and all.
>
> Vernon

Disclaimer:

I'm an EE, I've driven motors every which way, but I've never bought a
VFD, so I know theory but not particulars.

First:

If you disconnect the mill's on/off switch, put a big red shutoff button
connected to the VFD power out there. Make sure you can reach it when
your tie gets caught in the spindle (you _do_ dress formally when you
use your mill, right?).

Second:

A "constant torque" VFD is going to work, more or less, by figuring out
some of the motor's internal state and driving it's voltages
accordingly. Switching the motor leads is going to confuse the hell out
of it.

Whether or not this damages the VFD is very much a function of whether
the VFD is designed to protect itself. If you're a circuit designer you
can _always_ make a bullet proof circuit. You just can't always get
your product line manager to sign up to it ("don't waste time on that,
our customers won't notice that the thing goes up in smoke the way brand
XYZ doesn't").

Third:

If the thing is well designed, and if it has provisions for reversing
the motor and for dynamic breaking, they'll certainly work better than
using the motor switch. I'd wire them up, and find out if it fits my
definition of "well designed".

Fourth:

Don't forget that emergency stop button. Sharp spinning metal has an
unfortunate effect on flesh.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Posted by Vernon on October 6, 2008, 1:47 pm
Please log in for more thread options


> Vernon wrote:
> > Gentlemen,
>
> > I bought a Hitachi SJ200-022NFU2 model, 3 HP VFD to control my "new"
> > mill, which has a 2HP 3 phase motor.
>
> > This model, a "constant torque" VFD, is versatile and sophisticated,
> > and contains control options far beyond my needs and expertise.
>
> > I have carefully and almost completely read the owner's manual. =A0The
> > basic installation is simple enough. =A0You bring in the 2 legs of 220V
> > single phase from a 30 amp fuse or breaker, and connect these to
> > inputs 1 and 3. =A0You ground the mounted VFD and the mill motor in a
> > star pattern. =A0You connect the appropriate 3 outputs from the VFD to
> > the motor.
>
> > You go through an initial programming sequence, setting up certain
> > basic parameters. =A0You power up the VFD. =A0You verify certain that
> > certain pre-conditions are met and that certain LEDs are on or off on
> > the keypad. =A0You take a deep breath, make the sign of the cross, and
> > press START.
>
> > After that the going gets sort of tough. =A0Here are a couple of things
> > I don't understand. =A0I will humbly accept your guidance.
>
> > First, it is my understanding that it is possibly fatal to the VFD to
> > switch the motor on or off from the mill's own on-off switch, or to
> > otherwise control the mill (instant reverse for example) EXCEPT
> > through the VFD's programmable circuits.
>
> > This leads to the following questions:
>
> > 1) Do I remove the mill's on-off switch completely or otherwise wire
> > it permanently in the ON position?
> > 2) Do I similarly wire around the wires going to and from the mill's
> > FORWARD - REVERSE toggle switch and re-route these wires to the VFD's
> > programmable inputs/outputs?
>
> > There was previously some discussion here about whether a VFD can
> > adequately handle the mill's instant reverse. =A0However, upon careful
> > reading of the manual the VFD does seem to have a programmable "node"
> > that allows for this. =A0Apparently this can be tweaked a couple of
> > ways. =A0One of these involves installing additional resistors. =A0Anot=
her
> > SEEMS to provide for programming the injection of a DC current into
> > the motor to stop it from coasting. =A0I think these two things are
> > related but I'm not sure.
>
> > I think I can get the thing installed this weekend so that it will at
> > least start and run. =A0However, my brain is a lot murkier as regards
> > these programmable controls.
>
> > Thanks to one and all.
>
> > Vernon
>
> Disclaimer:
>
> I'm an EE, I've driven motors every which way, but I've never bought a
> VFD, so I know theory but not particulars.
>
> First:
>
> If you disconnect the mill's on/off switch, put a big red shutoff button
> connected to the VFD power out there. =A0Make sure you can reach it when
> your tie gets caught in the spindle (you _do_ dress formally when you
> use your mill, right?).
>
> Second:
>
> A "constant torque" VFD is going to work, more or less, by figuring out
> some of the motor's internal state and driving it's voltages
> accordingly. =A0Switching the motor leads is going to confuse the hell ou=
t
> of it.
>
> Whether or not this damages the VFD is very much a function of whether
> the VFD is designed to protect itself. =A0If you're a circuit designer yo=
u
> can _always_ make a bullet proof circuit. =A0You just can't always get
> your product line manager to sign up to it ("don't waste time on that,
> our customers won't notice that the thing goes up in smoke the way brand
> XYZ doesn't").
>
> Third:
>
> If the thing is well designed, and if it has provisions for reversing
> the motor and for dynamic breaking, they'll certainly work better than
> using the motor switch. =A0I'd wire them up, and find out if it fits my
> definition of "well designed".
>
> Fourth:
>
> Don't forget that emergency stop button. =A0Sharp spinning metal has an
> unfortunate effect on flesh.
>
> --
>
> Tim Wescott
> Wescott Design Serviceshttp://www.wescottdesign.com
>
> Do you need to implement control loops in software?
> "Applied Control Theory for Embedded Systems" gives you just what it says=
.
> See details athttp://www.wescottdesign.com/actfes/actfes.html- Hide quote=
d text -
>
> - Show quoted text -

Tim. On behalf of my tender flesh I thank you! V

Posted by David Lesher on October 6, 2008, 2:10 pm
Please log in for more thread options



>Vernon wrote:

>Disclaimer:

>I'm an EE, I've driven motors every which way, but I've never bought a
>VFD, so I know theory but not particulars.

Meetoo..

>First:

>If you disconnect the mill's on/off switch, put a big red shutoff button
>connected to the VFD power out there. Make sure you can reach it when
>your tie gets caught in the spindle (you _do_ dress formally when you
>use your mill, right?).

Second:

See First: It's the most important aspect.

Depending on the VFD, maybe it has a shutdown function, but don't depend
on it. I'd have a direct 3-phase pushbutton, the latching kind. [Push in,
it stays in until unlatched.] Use an aux contact for the VFD.


--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Posted by Vernon on October 6, 2008, 2:22 pm
Please log in for more thread options


> >Vernon wrote:
> >Disclaimer:
> >I'm an EE, I've driven motors every which way, but I've never bought a
> >VFD, so I know theory but not particulars.
>
> Meetoo..
>
> >First:
> >If you disconnect the mill's on/off switch, put a big red shutoff button
> >connected to the VFD power out there. =A0Make sure you can reach it when
> >your tie gets caught in the spindle (you _do_ dress formally when you
> >use your mill, right?).
>
> Second:
>
> See First: It's the most important aspect.
>
> Depending on the VFD, maybe it has a shutdown function, but don't depend
> on it. I'd have a direct 3-phase pushbutton, the latching kind. [Push in,
> it stays in until unlatched.] Use an aux contact for the VFD.
>
> --
> A host is a host from coast to coast.................wb8...@nrk.com
> & no one will talk to a host that's close........[v].(301) 56-LINUX
> Unless the host (that isn't close).........................pob 1433
> is busy, hung or dead....................................20915-1433

Dave,

"Depending on the VFD, maybe it has a shutdown function, but don't
depend
on it. I'd have a direct 3-phase pushbutton, the latching kind. [Push
in,
it stays in until unlatched.] Use an aux contact for the VFD."

I did not understand this. The VFD manual says to have a disconnect
device but not to use it except in an emergency. Obviously, getting
entwined in rotating machinery is an emergency and trumps trashing the
VFD.

I will try to get a picture of the controls on the mill and publish
this. Hopefully y'all will take a look.

Thanks! Vernon



Similar ThreadsPosted
Re: WTB bench mill near Seattle April 1, 2006, 10:11 pm
Care and feeding of KBC bench mill October 12, 2008, 11:37 pm
Is this trailer properly balanced? April 19, 2008, 4:01 pm
Everyone properly steal beyond delicate rough weddings. December 4, 2007, 4:54 pm
when did Tom find below all the repayments? We can't chase containers unless Osama will properly show afterwards August 12, 2007, 6:01 pm
lots of considerable stands surround Ramsi, and they properly urge Stephanie too August 12, 2007, 9:23 pm
Saw bench repair January 23, 2007, 4:50 am
Bench Grinder December 25, 2007, 8:55 pm
Wood Bench May 3, 2008, 11:11 pm
FS: LOGAN 10" BENCH LATHE September 19, 2006, 10:14 am

Contact Us | Privacy Policy

XML SitemapXML Sitemap