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

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

On Oct 6, 12:36*pm, Tim Wescott wrote:
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 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 quoted text -

- Show quoted text -

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

Tim Wescott writes:

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
& 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

On Oct 6, 1:10*pm, David Lesher wrote:
Tim Wescott writes:
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
& 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

Vernon wrote:
On Oct 6, 1:10 pm, David Lesher wrote:
Tim Wescott writes:
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
& 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.


There are bazillions of things that can go wrong inside of an electronic
device that'll make it 'stick on'. Unless your VFD has been
specifically engineered so that you can trust your life to its built-in
shutdown, use an external shutdown.

Here's a test to see if the VFDs built-in shutdown is life-rated.
Answer each of the below questions "yes" or "no", then score the
indicated number of points for each "yes" answer, no points for "no".
Add up the point scores of every question. If the score is greater than
99, then you can trust the VFD with your life. Otherwise, use an
external shut down.

Does the VFD cost as much as a new Cessna? (100 points).

--

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

Tim Wescott writes:


There are bazillions of things that can go wrong inside of an electronic
device that'll make it 'stick on'. Unless your VFD has been
specifically engineered so that you can trust your life to its built-in
shutdown, use an external shutdown.

Better than my wording. except I'd say "external emergency shutdown"
to be explicit. No reason not to have other ones.

Here's another case: A mag-locked exit door, with an EXIT button
adjacent. Every code I have seen requires that to be a NC pushbutton, in
series with the lock. Push it, the lock has no power, period. You escape
the fire.

Another example of safety design: it's considered bad form to have a
microwave oven running with the door open. So it has two sets of door
switches that, if either opens, the oven is off.

PLUS, there's a third switch that CLOSES when the door is open. If
somehow, power IS still on, its contacts short out the power and smoke
something [fuse/breaker/etc.]

--
A host is a host from coast to
& 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

Vernon writes:

"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.


Get a pushbutton, a big industrial one. Allen Bradley comes to mind. They
are basically Legos; you start with the basic button and add contacts of
the type needed.

It should have 3 contacts rated for the full current of the motor. They
will be closed in OUT mode, but open when pushed in. Wire in series
with all three legs going to the motor..

Have a low current 4th contact going to the VFD shutdown connection.

This will break the power feed to your mill when hit, AND send a shutdown
to the VFD. [It may take a while to turn off, however, as compared to the
button. Maybe even as much a second or two; see what the VFD Fine Manual
says.]

This way, even if the shutdown command does not work, the power *is* off.

The shutdown pushbutton will be expensive new. There are millions surplus
but it will be tricky to mail-order same. If you have a surplus place
nearby....

--
A host is a host from coast to
& 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

David Lesher wrote:

Vernon writes:

"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.

Get a pushbutton, a big industrial one. Allen Bradley comes to mind. They
are basically Legos; you start with the basic button and add contacts of
the type needed.

It should have 3 contacts rated for the full current of the motor. They
will be closed in OUT mode, but open when pushed in. Wire in series
with all three legs going to the motor..

Have a low current 4th contact going to the VFD shutdown connection.

This will break the power feed to your mill when hit, AND send a shutdown
to the VFD. [It may take a while to turn off, however, as compared to the
button. Maybe even as much a second or two; see what the VFD Fine Manual
says.]

This way, even if the shutdown command does not work, the power *is* off.

The shutdown pushbutton will be expensive new. There are millions surplus
but it will be tricky to mail-order same. If you have a surplus place
nearby....

The E-stop switch belongs on the power feed *to* the VFD, *not* on the
motor leads from the VFD, otherwise you just have a "VFD destruct"
button. The diagrams in the VFD manual should show the proper wiring for
an emergency stop.

On Mon, 6 Oct 2008 10:08:56 -0700 (PDT), Vernon
wrote:


1) Do I remove the mill's on-off switch completely or otherwise wire
it permanently in the ON position?

If this is simply a switch in the incoming line, use it to feed power
to the VFD.

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?

Yes, though I prefer three pushbuttons -- FWD/OFF/REV.

Plan on setting up a pot for speed adjustment. If you use the drive's
keypad for speed changes you'll lose much of the convenience the drive
offers.


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.

You'll have to experiment to see what works for you. On many drives
the accel and decel settings are set in seconds even though the actual
effect is "seconds per 60 Hz." The result is that at low speed
settings the reverse is very quick. The most obvious application is
for power tapping, where it's often convenient to drill at high speed,
then turn the speed down to tap, and reverse to back the tap out. If
your drive is one that behaves as I've described above, the tap
reversal will be almost instantaneous at 10 Hz with, say, a 1 second
(at 60 Hz) accel/decel setting. If your drive's manual is silent or
vague on this point, you'll have to experiment to determine its actual
behavior.


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

This is a block diagram of how I'd recommend you wire you mill. (View
with a fixed pitch font.)

(Line In) - (Main Power Switch) - ( VFD ) - (Motor)
^ ^
| |
(FWD/OFF/REV) (Speed Pot)

Here's photo of that setup on my mill:
http://www.suscom-maine.net/~nsimmons/news/MillVFD.JPG

--
Ned Simmons

On my mill, I have 220v single phase coming in, going through a VFD,
then a FWD-OFF-REV switch, and into the motor.

I do not use the reversing switch to turn or reverse the motor. I use
the VFD for it.

What I do use the motor is to make the motor go in the right direction
when switching in and out of backgear. If I switch to a slow speed via
backgear, then all things being kept the same, the spind would turn
backwards when I turn VFD into FWD. That's stupid. So, I maDE A RULE
for myself, whenever I switch the mill to/from the backgear, I flip
the FWD/REV switch on the mill to keep FWD rotation the same. Works
for me.

I use the VFD for plug reversing.

i

I use/install vfds almost every day.

Most have a STOP input or even an Estop input

Ive never seen one fail before. Ever

Hitting the Stop button generally makes sure the drive shuts the
spindle etc etc virtually instantly.

Turning off the power insures the spindle etc coasts to a stop.

Are you sure that you want to have the lathe spindle coast to a stop
when its got your tie in a chuck jaw?

Just thought Id mention that ........

Gunner

Whenever a Liberal utters the term "Common Sense approach"....grab your
wallet, your ass, and your guns because the sombitch is about to do
something damned nasty to all three of them.

On Oct 6, 8:39*pm, Gunner Asch wrote:
I use/install vfds almost every day.

Most have a STOP input or even an Estop input

Ive never seen one fail before. Ever

Hitting the Stop button generally makes sure the drive shuts the
spindle etc etc virtually instantly.

Turning off the power insures the spindle etc coasts to a stop.

Are you sure that you want to have the lathe spindle coast to a stop
when its got your tie in a chuck jaw?

Just thought Id mention that ........

Gunner

*Whenever a Liberal utters the term "Common Sense approach"....grab your
*wallet, your ass, and your guns because the sombitch is about to do
*something damned nasty to all three of them.

Gunner. Thanks for your valuable input. I would be more than happy
to feed ALL my ties into the lathe spindle provided my neck ain't in
'em!

I am continuing to soak up the manual along with everybody's
collective input. I intend to proceed to do the installation and the
basic start-up test and then stop at the threshold of all the stuff I
still don't understand. No doubt I will have many more questions
soon. Hopefully, they will be more specific and intelligently
articulated.

Thanks to all.

V

On 2008-10-06, 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.

Sounds like a good choice. The 3HP rating of the VFD should
provide sufficient derating when running a 2HP motor.

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.

Some have a jumper between input 2 and one of the others, but
yours is probably newer than mine, which was one of the previous batch
which were being sold off cheap to make room for the newer ones such as
what you have.

You ground the mounted VFD and the mill motor in a
star pattern.

Actually -- you only ground the motor's *case* or frame, not the
center tap of the motor's windings. I would be tempted to call it a Wye
(Y) instead of a star, since it is only three phase, though the other
term can apply as well.

*But* -- a Bridgeport three-phase motor is dual voltage, and you
will be using it wired for 240V, not 480V. Wired that way, there is a
Wye which has the common point buried inside the motor, and you make a
second Wye by joining (and insulating) the proper ends of the other
wires, and the outside ends get connected in parallel with the first
Wye. Thus you can't really get to the center point of the primary Wye,
without tearing the motor apart and probably voiding whatever warranty
is still present. The Wye (or you could run a Delta if the motor were
designed for it) can totally float. The ground to the frame makes the
safety ground you need.

You connect the appropriate 3 outputs from the VFD to
the motor.

Yes.

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 is generally correct. The exception can be found when the
rating of the VFD is sufficiently larger than the motor's rating, and
there is as sufficient length of cable to act as capacitive bypass. As
an example -- my Nichols horizontal mill (1HP motor) is across the shop
from the 7.5 HP VFD -- too far to easily run the control wires, but I
can get away with switching it at the mill end of the cable, and even
with plug reversing.

But for any reasonable rating match, you should not do this,
especially if the machine and motor are close to the VFD.

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?

No -- you wire directly from the mill's motor to the VFD --
skipping the on-off switch and the forward-reverse switch. (Note that
some machines, such as the BOSS-3 CNC version of the Bridgeport Series-1
have a buried reversing relay (a double contactor interlocked so only
one direction can be energized at a time). Anyway -- with the wire
going directly from the motor to the VFD, you will have bypassed this as
well -- if it exists.

Now -- rip out the wiring on the on/off switch and the
forward/reverse switch. (Are they not all one switch on your machine --
forward/stop/reverse?) and run the switch contacts into the VFD's
command terminals, so your original switches tell the VFD to start the
motor and in which direction. It is best to use shielded wire for this,
with the shield connected to the ground on the control logic terminals,
since electrical noise spikes could otherwise be picked up by the wires
and perhaps produce undesired activity on the motor.

You probably also want to add another small box under the
direction switch to hold a potentiometer to allow varying the speed
between whatever you have programmed as "full speed" and a dead stop.

Don't run the motor very slow for long, because you will lose
the cooling from the internal fan on the motor's shaft.

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?

Direct from motor to the VFD -- skipping all switches on the
machine.

Then wire the switches to tell the VFD what you want it to do.
Note that using the original switches in the original positions will
keep you reaching for the right controls, so if you are ever in a
position to use someone else's machine, your habits will be right in
case you need to stop it in a hurry.

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.

Two ways to the same end.

The resistor is to absorb power generated by the spinning motor
to slow it down more quickly.

The DC through the motor will stop it more quickly.

As soon as the motor reaches a stop, the VFD can automatically
accelerate it to the desired speed in the other direction.

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.

Play with them for a while (perhaps just connected to the motor
with no mill cutting taking place) -- learn what they do -- and then
leave them set to whatever works best. The only controls you really
need are within reach on the machine -- the forward/stop/reverse switch
and the speed control pot.

Another thing which you may or may not know -- depending on
whether you have used other Bridgeports. When you engage the back-gear
with the lever on the right hand side of the head, the spindle direction
will reverse. It might be worth while adding a switch in a chip-proof
housing to sense the position of the lever to reverse what your forward
and reverse switch does. (Of course, this is the reverse of what I was
saying above to keep the action of the switches standard. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Oct 7, 10:24*pm, "DoN. Nichols" wrote:
On 2008-10-06, 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.

* * * * Sounds like a good choice. *The 3HP rating of the VFD should
provide sufficient derating when running a 2HP motor.

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.

* * * * Some have a jumper between input 2 and one of the others, but
yours is probably newer than mine, which was one of the previous batch
which were being sold off cheap to make room for the newer ones such as
what you have.

* * * * * * * * *You ground the mounted VFD and the mill motor in a
star pattern.

* * * * Actually -- you only ground the motor's *case* or frame, not the
center tap of the motor's windings. *I would be tempted to call it a Wye
(Y) instead of a star, since it is only three phase, though the other
term can apply as well.

* * * * *But* -- a Bridgeport three-phase motor is dual voltage, and you
will be using it wired for 240V, not 480V. *Wired that way, there is a
Wye which has the common point buried inside the motor, and you make a
second Wye by joining (and insulating) the proper ends of the other
wires, and the outside ends get connected in parallel with the first
Wye. *Thus you can't really get to the center point of the primary Wye,
without tearing the motor apart and probably voiding whatever warranty
is still present. *The Wye (or you could run a Delta if the motor were
designed for it) can totally float. *The ground to the frame makes the
safety ground you need.

* * * * * * * *You connect the appropriate 3 outputs from the VFD to
the motor.

* * * * Yes.

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 is generally correct. *The exception can be found when the
rating of the VFD is sufficiently larger than the motor's rating, and
there is as sufficient length of cable to act as capacitive bypass. *As
an example -- my Nichols horizontal mill (1HP motor) is across the shop
from the 7.5 HP VFD -- too far to easily run the control wires, but I
can get away with switching it at the mill end of the cable, and even
with plug reversing.

* * * * But for any reasonable rating match, you should not do this,
especially if the machine and motor are close to the VFD.

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?

* * * * No -- you wire directly from the mill's motor to the VFD --
skipping the on-off switch and the forward-reverse switch. *(Note that
some machines, such as the BOSS-3 CNC version of the Bridgeport Series-1
have a buried reversing relay (a double contactor interlocked so only
one direction can be energized at a time). *Anyway -- with the wire
going directly from the motor to the VFD, you will have bypassed this as
well -- if it exists.

* * * * Now -- rip out the wiring on the on/off switch and the
forward/reverse switch. *(Are they not all one switch on your machine --
forward/stop/reverse?) and run the switch contacts into the VFD's
command terminals, so your original switches tell the VFD to start the
motor and in which direction. *It is best to use shielded wire for this,
with the shield connected to the ground on the control logic terminals,
since electrical noise spikes could otherwise be picked up by the wires
and perhaps produce undesired activity on the motor.

* * * * You probably also want to add another small box under the
direction switch to hold a potentiometer to allow varying the speed
between whatever you have programmed as "full speed" and a dead stop.

* * * * Don't run the motor very slow for long, because you will lose
the cooling from the internal fan on the motor's shaft.

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?

* * * * Direct from motor to the VFD -- skipping all switches on the
machine.

* * * * Then wire the switches to tell the VFD what you want it to do.
Note that using the original switches in the original positions will
keep you reaching for the right controls, so if you are ever in a
position to use someone else's machine, your habits will be right in
case you need to stop it in a hurry.

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.

* * * * Two ways to the same end.

* * * * The resistor is to absorb power generated by the spinning motor
to slow it down more quickly.

* * * * The DC through the motor will stop it more quickly.

* * * * As soon as the motor reaches a stop, the VFD can automatically
accelerate it to the desired speed in the other direction.

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.

* * * * Play with them for a while (perhaps just connected to the motor
with no mill cutting taking place) -- learn what they do -- and then
leave them set to whatever works best. *The only controls you really
need are within reach on the machine -- the forward/stop/reverse switch
and the speed control pot.

* * * * Another thing which you may or may not know -- depending on
whether you have used other Bridgeports. *When you engage the back-gear
with the lever on the right hand side of the head, the spindle direction
will reverse. *It might be worth while adding a switch in a chip-proof
housing to sense the position of the lever to reverse what your forward
and reverse switch does. *(Of course, this is the reverse of what I was
saying above to keep the action of the switches standard. :-)

* * * * Enjoy,
* * * * * * * * DoN.

--
*Email: * * | Voice (all times): (703) 938-4564
* * * * (too) near Washington D.C. |http://www.d-and-d.com/dnichols/DoN.html
* * * * * *--- Black Holes are where God is dividing by zero ---

Don. That was very very helpful. However, I bitterly regret to
inform you that my mill is not a Bridgeport. It is a common garden
variety Taiwanese bench mill. It's like a drill press on steroids.
Ironically, I bought it for two reasons: First, there were no
bidders. Second, I mistakenly thought that it was single phase and
that this would be the biggest thing to be had that WOULD operate on
single phase.

Too late, I discovered that it was 3 phase. Thus, I had to pop down
this VFD rabbit hole. Had I know in advance how wunnerful and
versatile they are, I coulda/ shoulda bought a full sized mill. But
time ain't over for me yet. So maybe there's another mill in my
future.

Best. Vernon