Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric

wrote in message ...
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric

A perfect example of where the use of a buck boost transformer is indicated.

On 10/26/2012 6:35 PM, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric
If you ever get to Central Oregon (Redmond), I will give you three
buck/boost transformers that will work for you. I will have to check the
voltage, but I think it is 20 volt buck/boost. They were part of an old
wave solder machine. I can give you the exact spec if interested. I
would love to get rid of them.

Paul

wrote:

And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:

http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I have some doubts this is your problem at all. Most VFDs will
handle a wide range of input voltages. I'd check you braking
resistors to be sure they are still working. There is also the
possibility the transistor that turns on the braking resistor
has gone bad. With 22 KVa this must be a pretty big motor and VFD, so
the braking resistor must also be pretty big.

Jon

"Jon Elson" wrote in message
...
wrote:

And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:

http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I have some doubts this is your problem at all. Most VFDs will
handle a wide range of input voltages. I'd check you braking
resistors to be sure they are still working. There is also the
possibility the transistor that turns on the braking resistor
has gone bad. With 22 KVa this must be a pretty big motor and VFD, so
the braking resistor must also be pretty big.


Actually it's a very common problem at least with the older fanuc drives.

But, I suggest he should also check the manual over really good; IF there is
a jumper setting that specifies an external braking resistor and there is
not an external resistor installed then it will also cause overvoltage to
occur on the dc buss.

Jon Elson writes:

Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I have some doubts this is your problem at all. Most VFDs will
handle a wide range of input voltages. I'd check you braking
resistors to be sure they are still working. There is also the
possibility the transistor that turns on the braking resistor
has gone bad. With 22 KVa this must be a pretty big motor and VFD, so
the braking resistor must also be pretty big.


I echo the above.

Can you disable the regeneration and use a {?different} braking
resistor? It's designed to pump power back into the grid vs
waste it; and I suspect your rotary converter does not like it.

Besides, wasting is the good old American way!

Or can you feed the VFD with the single-phase line?

David Lesher wrote:


I echo the above.

Can you disable the regeneration and use a {?different} braking
resistor? It's designed to pump power back into the grid vs
waste it; and I suspect your rotary converter does not like it.

Oh, it is a regenerating VFD! That is different, if true.
Yes, then the input voltage could interfere with the
regeneration system. Usually regeneration is only used on really
big drives, 100 Hp and up, as it definitely costs a lot more to
do. But, maybe they chose this to avoid having to have a large
braking resistor with cooling fans.

Or can you feed the VFD with the single-phase line?
Not likely a 22 KVa drive would accept single phase, and
especially if a regenerative drive it definitely would not.

Also, the drive may be very unhappy with a rotary phase
converter. Not exactly sure what an RPC would do when
the drive starts sending 3-phase energy back to it, but it
is pretty likely it does NOT behave like a true 3-phase
supply. My guess is the "wild leg" would surge.

Jon

On Fri, 26 Oct 2012 19:28:54 -0700, Paul Drahn
wrote:

On 10/26/2012 6:35 PM, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric
If you ever get to Central Oregon (Redmond), I will give you three
buck/boost transformers that will work for you. I will have to check the
voltage, but I think it is 20 volt buck/boost. They were part of an old
wave solder machine. I can give you the exact spec if interested. I
would love to get rid of them.

Paul
Greetings Paul,
I would drive down to Redmond to get those. I have a friend who lives
in Portland so maybe I could visit with him. Weekends would be best
for me but I could drive down on a weekday. Before I plan the trip it
would be best to have the specs so that I know they will work. How big
and heavy are these things?
Thanks,
Eric

On Fri, 26 Oct 2012 23:47:18 -0500, Jon Elson
wrote:

David Lesher wrote:


I echo the above.

Can you disable the regeneration and use a {?different} braking
resistor? It's designed to pump power back into the grid vs
waste it; and I suspect your rotary converter does not like it.

Oh, it is a regenerating VFD! That is different, if true.
Yes, then the input voltage could interfere with the
regeneration system. Usually regeneration is only used on really
big drives, 100 Hp and up, as it definitely costs a lot more to
do. But, maybe they chose this to avoid having to have a large
braking resistor with cooling fans.

Or can you feed the VFD with the single-phase line?
Not likely a 22 KVa drive would accept single phase, and
especially if a regenerative drive it definitely would not.

Also, the drive may be very unhappy with a rotary phase
converter. Not exactly sure what an RPC would do when
the drive starts sending 3-phase energy back to it, but it
is pretty likely it does NOT behave like a true 3-phase
supply. My guess is the "wild leg" would surge.

Jon
I think the wild leg is surging. But the drive is operating at about
20 volts above its rating. And it really is a regenerating drive
according to the manual. The drive is inside a cabinet with little
ventilation so I can't imagine there would be enough cooling to get
rid of the heat from braking resistors. All the machines I have seen
with braking resistors have them outside of the cabinet that holds all
of the electronics. Before I bought this machine it was connected to a
Phase Perfect solid state phase converter the drive didn't have
overvoltage faults then. Only when the Phase Perfect had some failing
filter caps and when the power coming into the building would spike.
Eric

On Fri, 26 Oct 2012 20:19:47 -0700, "PrecisionmachinisT"
wrote:


"Jon Elson" wrote in message
m...
wrote:

And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:

http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I have some doubts this is your problem at all. Most VFDs will
handle a wide range of input voltages. I'd check you braking
resistors to be sure they are still working. There is also the
possibility the transistor that turns on the braking resistor
has gone bad. With 22 KVa this must be a pretty big motor and VFD, so
the braking resistor must also be pretty big.


Actually it's a very common problem at least with the older fanuc drives.

But, I suggest he should also check the manual over really good; IF there is
a jumper setting that specifies an external braking resistor and there is
not an external resistor installed then it will also cause overvoltage to
occur on the dc buss.

The drive is not a Fanuc drive, it is a Fuji product. But I will check
to see if there is a way to add an external braking resistor.
Eric

Jon Elson writes:


Oh, it is a regenerating VFD! That is different, if true.
Yes, then the input voltage could interfere with the
regeneration system. Usually regeneration is only used on really
big drives, 100 Hp and up, as it definitely costs a lot more to
do. But, maybe they chose this to avoid having to have a large
braking resistor with cooling fans.

The issue is the regen system must dump the scavaged power
*somewhere*. With 3ph grid, that's no issue. But with
your rotary inverter, it sounds like it is.

The only answer that springs to mind is adding a 2nd load to the
rotary converter; a lamp bank or resistor bank. It would have to
absorb the shed power. It's not going to be small.

On 2012-10-27, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm.

Hmm ... this sounds like it is missing a braking resistor.
Perhaps it has one and it has fried/opened?

But it is possible that starting from the higher line voltage,
it might be more likely to trip the limits. (And, BTW, have you checked
how well balanced your rotary converter is? It is common for one leg to
be significantly higher than the others, and this can be helped
(somewhat) with tuning capacitors -- though since you are driving
multiple machines with it, it makes the balance just right for *one*
machine, and perhaps worse for others.

The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf

Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.

It might be easier to use a single buck transformer on the
single phase 240 VAC into the VFD. But your 22 KVA says that it will
need to handle something like 91 A (so 100 A for a round number), which
is a massive transformer. Hmm ... voltage needed to drop your peak 250
V to 240 V for a reasonable maximum would be 10 V (maybe 12 V would be
easier to find), which would be about a 1.2 KVA transformer -- not quite
as bad as it could be. Your VFD might need to be a bit bigger to
provide sufficient spindle output power from single phase (and check
that it will *run* from single phase). Anyway, you would need the power
to be Wye, not Delta format -- at least on the output side of a big
transformer to allow the buck-boost to work cleanly.

BTW It is likely that the rest of the machine (separate from the
VFD and spindle motor) really only needs single phase, which it
derives from one phase of the three phase input, so you likely
don't need the the rotary converter at all for that machine.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
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 27 Oct 2012 18:30:16 GMT, "DoN. Nichols"
wrote:

On 2012-10-27, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm.

Hmm ... this sounds like it is missing a braking resistor.
Perhaps it has one and it has fried/opened?

But it is possible that starting from the higher line voltage,
it might be more likely to trip the limits. (And, BTW, have you checked
how well balanced your rotary converter is? It is common for one leg to
be significantly higher than the others, and this can be helped
(somewhat) with tuning capacitors -- though since you are driving
multiple machines with it, it makes the balance just right for *one*
machine, and perhaps worse for others.

The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf

Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.

It might be easier to use a single buck transformer on the
single phase 240 VAC into the VFD. But your 22 KVA says that it will
need to handle something like 91 A (so 100 A for a round number), which
is a massive transformer. Hmm ... voltage needed to drop your peak 250
V to 240 V for a reasonable maximum would be 10 V (maybe 12 V would be
easier to find), which would be about a 1.2 KVA transformer -- not quite
as bad as it could be. Your VFD might need to be a bit bigger to
provide sufficient spindle output power from single phase (and check
that it will *run* from single phase). Anyway, you would need the power
to be Wye, not Delta format -- at least on the output side of a big
transformer to allow the buck-boost to work cleanly.

BTW It is likely that the rest of the machine (separate from the
VFD and spindle motor) really only needs single phase, which it
derives from one phase of the three phase input, so you likely
don't need the the rotary converter at all for that machine.

Good Luck,
DoN.
Greetings DoN,
The machine control does indeed need 3 phase power. The Fanuc control
uses a 3 phase xmfr to condition the voltage for the control circuits
and of course that power is rectified but it looks like the servo amps
use 3 phase directly. Of course somewhere in the amp the ac gets
rectified. The spindle drive will only accept 3 phase power. There is
no braking resistor option either. Looking at the manual it says that
the power is dumped back into the 3 phase source. If I do use 3 buck
xmfrs to lower the voltage will the xmfrs themselves be able to absorb
enough energy to be useful in that regard? Or will their only
advantage be the lower voltage? The xmfrs that Paul Drahn offered to
me will drop the voltage 20 volts. This is fine according to the
manual. When set at the 230 volt setting the drive will operate all
the way down to 198 volts.
ERic

On Sat, 27 Oct 2012 18:10:11 +0000 (UTC), David Lesher
wrote:

Jon Elson writes:


Oh, it is a regenerating VFD! That is different, if true.
Yes, then the input voltage could interfere with the
regeneration system. Usually regeneration is only used on really
big drives, 100 Hp and up, as it definitely costs a lot more to
do. But, maybe they chose this to avoid having to have a large
braking resistor with cooling fans.

The issue is the regen system must dump the scavaged power
*somewhere*. With 3ph grid, that's no issue. But with
your rotary inverter, it sounds like it is.

The only answer that springs to mind is adding a 2nd load to the
rotary converter; a lamp bank or resistor bank. It would have to
absorb the shed power. It's not going to be small.
How would I add a resistor bank that wouldn't be using power all the
time but still be able to absorb surges from the spindle drive? I use
the phase converter to run several machines at once in my shop. It
doesn't seem to matter if only the one lathe is running or if the
spindles on other machines are running, the spindle drive still alarms
out when decelerating. Not stopping though, just decelerating.
Eric

On 10/27/2012 10:36 AM, wrote:
On Fri, 26 Oct 2012 19:28:54 -0700, Paul Drahn
wrote:

On 10/26/2012 6:35 PM, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric
If you ever get to Central Oregon (Redmond), I will give you three
buck/boost transformers that will work for you. I will have to check the
voltage, but I think it is 20 volt buck/boost. They were part of an old
wave solder machine. I can give you the exact spec if interested. I
would love to get rid of them.

Paul
Greetings Paul,
I would drive down to Redmond to get those. I have a friend who lives
in Portland so maybe I could visit with him. Weekends would be best
for me but I could drive down on a weekday. Before I plan the trip it
would be best to have the specs so that I know they will work. How big
and heavy are these things?
Thanks,
Eric
I will be at the plant Monday evening and will get all the specs then.

Paul

On Sat, 27 Oct 2012 12:55:01 -0700, Paul Drahn
wrote:

On 10/27/2012 10:36 AM, wrote:
On Fri, 26 Oct 2012 19:28:54 -0700, Paul Drahn
wrote:

On 10/26/2012 6:35 PM, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric
If you ever get to Central Oregon (Redmond), I will give you three
buck/boost transformers that will work for you. I will have to check the
voltage, but I think it is 20 volt buck/boost. They were part of an old
wave solder machine. I can give you the exact spec if interested. I
would love to get rid of them.

Paul
Greetings Paul,
I would drive down to Redmond to get those. I have a friend who lives
in Portland so maybe I could visit with him. Weekends would be best
for me but I could drive down on a weekday. Before I plan the trip it
would be best to have the specs so that I know they will work. How big
and heavy are these things?
Thanks,
Eric
I will be at the plant Monday evening and will get all the specs then.

Paul
Thanks Paul. I'm hoping your xmfrs will solve my problem.
Eric

writes:


How would I add a resistor bank that wouldn't be using power all the
time but still be able to absorb surges from the spindle drive?

You can't...

I use the phase converter to run several machines at once in
my shop. It doesn't seem to matter if only the one lathe is
running or if the spindles on other machines are running, the
spindle drive still alarms out when decelerating. Not stopping
though, just decelerating. Eric


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On Sun, 28 Oct 2012 00:30:09 +0000 (UTC), David Lesher
wrote:

writes:


How would I add a resistor bank that wouldn't be using power all the
time but still be able to absorb surges from the spindle drive?

You can't...

I use the phase converter to run several machines at once in
my shop. It doesn't seem to matter if only the one lathe is
running or if the spindles on other machines are running, the
spindle drive still alarms out when decelerating. Not stopping
though, just decelerating. Eric
Maybe I should have said using significant power.
Eric

On 2012-10-27, wrote:
On 27 Oct 2012 18:30:16 GMT, "DoN. Nichols"
wrote:

[ ... ]

BTW It is likely that the rest of the machine (separate from the
VFD and spindle motor) really only needs single phase, which it
derives from one phase of the three phase input, so you likely
don't need the the rotary converter at all for that machine.

Greetings DoN,
The machine control does indeed need 3 phase power. The Fanuc control
uses a 3 phase xmfr to condition the voltage for the control circuits
and of course that power is rectified but it looks like the servo amps
use 3 phase directly.

I know that the Bridgeport BOSS-3 (and at least through BOSS-6)
used three phase to power the steppers -- but used a single phase for
each stepper. A big three phase transformer to provide the voltages for
the stepper drivers, with a "mag amp" (saturable reactor) to reduce the
voltage when the stepper was stopped or moving slowly, to avoid the
motor overheating. (The idea of a constant current supply to the
stepper had either not yet occurred (1975), or it was too complex for
affordable electronics at the time.) But, if you had enough current
available from single a phase, and replaced that three phase transformer
with one large single phase one, or three smaller ones (depending on
what was available) you could happily run that from single phase. Then
you would only need three phase for the spindle motor, and today a VFD
is the way of choice for driving a single motor.

BTW Running that from a rotary converter increases the chances of
blowing the transistors used to drive the stepper. They were
2N3055 transistors, nominally rated for 60 or 80 VDC. The ones
which I pulled from the old electronics on my Bridgeport test
out on a curve tracer to something on the order of 120 to 180
VCE max. I suspect that they were selected for the higher
breakdown voltage. Anyway -- with the nominal 80V being applied
at full speed to the steppers, and with an unbalance from a
rotary converter, it would be very easy to over-voltage the
transistors at their normal rating. (Of course, I pulled the
stepper motors and replaced them with DC servo motors, and was
pretty close to being ready to add the computer and LinuxCNC to
put it back in service when the lubricator set it all on fire,
keeping me out of the shop until it is cleaned up (a liter of
Vactra No. 2 makes a *lot* of dark sooty smoke, and a *lot* of
heat, too. :-(

Of course somewhere in the amp the ac gets
rectified.

Of course -- and once it is DC -- who cares how many phases were
used to produce it. :-)

The spindle drive will only accept 3 phase power.

The VFD? Others are available, of course. It sounds like you
have a particularly large one, however, so a VFD which will accept
single phase would be rather expensive, unless you were really lucky. I
have (or perhaps had? I haven't been able to test it, and the case is
partially melted) one which was good for 30A input and output at 240
VAC, and it would quite happily run from single phase. This comes up to
just short of 10 HP using single phase ratings. A bit over 15 HP with
three phase power input, I believe. It was all of $100.00 at a hamfest
in the mid 1990s IIRC.

There is
no braking resistor option either. Looking at the manual it says that
the power is dumped back into the 3 phase source.

One which is nice in terms of the power bill (how many HP *is*
that spindle motor?), but which complicates things with a rotary
converter, as others have mentioned. No real bets on what will work or
not.

If I do use 3 buck
xmfrs to lower the voltage will the xmfrs themselves be able to absorb
enough energy to be useful in that regard?

They will try to dump it back into the rotary converter.

Or will their only
advantage be the lower voltage? The xmfrs that Paul Drahn offered to
me will drop the voltage 20 volts. This is fine according to the
manual. When set at the 230 volt setting the drive will operate all
the way down to 198 volts.

That sounds worth trying -- especially at the price.
(Depends on how far you have to drive to get them, of course. :-)

Did he have a current rating on the secondary?

You are getting your three phase from a rotary converter. Is it
wired to give you a Wye "Y" neutral point, or is it delta? I think that
for the buck-boost, you really want Wye to simplify the setup. Delta
would need isolation transformer in each phase as well. If you
connected the primarys to a delta source, and hooked the secondarys
between the corners of the delta and the load you would be applying
correction voltages at a weird phase relationship to the voltages at the
corners. But if you have your rotary converter using a Wye connection
in the idler motor, you should be fine.

Good Luck,
DoN.

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I have real 2 phase high voltage (two of 3 legs from the power
substation). (The Two phase high voltage was used here when this place
had a Sawmill on the site. Three phase is on both sides of the highway
with local poles for houses. My trunk off the main line is 1400' long.
I had 1600' but lost 200 in a bad storm and a tree fall.)

I have only single phase 240 in the shop. I spin up 3 phase in a rotary
and drive six transformers. Six ? - yes three large
voltage step up transformers with boost transformers on each output.


It has been working just fine. The core of the transformer absorbs
energy from voltages / currents dumped to it in the primary or secondary.

Since it goes into the core, it can come back out. When the tool goes
below that voltage / current value the transformer magnetic field will
start to collapse and will generate voltage / current as it needs.

Just like the motors do when they come under load and the load eases
off. Under load it draws more current to keep on going when the load
slacks off the magnetic field in the core begins to collapse and
generates the voltage/current.

Martin

On 10/27/2012 1:59 PM, wrote:
On 27 Oct 2012 18:30:16 GMT, "DoN. Nichols"
wrote:

On 2012-10-27, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm.

Hmm ... this sounds like it is missing a braking resistor.
Perhaps it has one and it has fried/opened?

But it is possible that starting from the higher line voltage,
it might be more likely to trip the limits. (And, BTW, have you checked
how well balanced your rotary converter is? It is common for one leg to
be significantly higher than the others, and this can be helped
(somewhat) with tuning capacitors -- though since you are driving
multiple machines with it, it makes the balance just right for *one*
machine, and perhaps worse for others.

The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf

Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.

It might be easier to use a single buck transformer on the
single phase 240 VAC into the VFD. But your 22 KVA says that it will
need to handle something like 91 A (so 100 A for a round number), which
is a massive transformer. Hmm ... voltage needed to drop your peak 250
V to 240 V for a reasonable maximum would be 10 V (maybe 12 V would be
easier to find), which would be about a 1.2 KVA transformer -- not quite
as bad as it could be. Your VFD might need to be a bit bigger to
provide sufficient spindle output power from single phase (and check
that it will *run* from single phase). Anyway, you would need the power
to be Wye, not Delta format -- at least on the output side of a big
transformer to allow the buck-boost to work cleanly.

BTW It is likely that the rest of the machine (separate from the
VFD and spindle motor) really only needs single phase, which it
derives from one phase of the three phase input, so you likely
don't need the the rotary converter at all for that machine.

Good Luck,
DoN.
Greetings DoN,
The machine control does indeed need 3 phase power. The Fanuc control
uses a 3 phase xmfr to condition the voltage for the control circuits
and of course that power is rectified but it looks like the servo amps
use 3 phase directly. Of course somewhere in the amp the ac gets
rectified. The spindle drive will only accept 3 phase power. There is
no braking resistor option either. Looking at the manual it says that
the power is dumped back into the 3 phase source. If I do use 3 buck
xmfrs to lower the voltage will the xmfrs themselves be able to absorb
enough energy to be useful in that regard? Or will their only
advantage be the lower voltage? The xmfrs that Paul Drahn offered to
me will drop the voltage 20 volts. This is fine according to the
manual. When set at the 230 volt setting the drive will operate all
the way down to 198 volts.
ERic

David Lesher wrote:

writes:


How would I add a resistor bank that wouldn't be using power all the
time but still be able to absorb surges from the spindle drive?

You can't...

I use the phase converter to run several machines at once in
my shop. It doesn't seem to matter if only the one lathe is
running or if the spindles on other machines are running, the
spindle drive still alarms out when decelerating. Not stopping
though, just decelerating. Eric


The typical VFD (not the regenerating type) has a transistor
that switches the braking resistor on when the DC bus voltage
rises from energy coming back from the motor during deceleration.
It is only switched on for a fraction of a second to keep the
DC bus voltage below some preset threshold. So, the braking
resistor will not be dissipating power until it is needed.

Regenerating type VFDs would not have a braking resistor.

Jon

"Martin Eastburn" wrote in message
...
I have real 2 phase high voltage (two of 3 legs from the power substation).
(The Two phase high voltage was used here when this place had a Sawmill on
the site. Three phase is on both sides of the highway with local poles for
houses. My trunk off the main line is 1400' long. I had 1600' but lost
200 in a bad storm and a tree fall.)

I have only single phase 240 in the shop. I spin up 3 phase in a rotary
and drive six transformers. Six ? - yes three large
voltage step up transformers with boost transformers on each output.


It has been working just fine. The core of the transformer absorbs
energy from voltages / currents dumped to it in the primary or secondary.

Since it goes into the core, it can come back out. When the tool goes
below that voltage / current value the transformer magnetic field will
start to collapse and will generate voltage / current as it needs.

Just like the motors do when they come under load and the load eases off.
Under load it draws more current to keep on going when the load
slacks off the magnetic field in the core begins to collapse and generates
the voltage/current.



technically, he only needs 2 buck boost transformers to do the job but 3
smaller ones would do it just as well.

And in your your case, it sounds like (probably) you actually do have three
phase power, just that it's in the form that is commonly called "open delta"

http://www.youtube.com/watch?v=V7_ulixULiw

On 28 Oct 2012 02:17:43 GMT, "DoN. Nichols"
wrote:

On 2012-10-27, wrote:
On 27 Oct 2012 18:30:16 GMT, "DoN. Nichols"
wrote:

[ ... ]

BTW It is likely that the rest of the machine (separate from the
VFD and spindle motor) really only needs single phase, which it
derives from one phase of the three phase input, so you likely
don't need the the rotary converter at all for that machine.

Greetings DoN,
The machine control does indeed need 3 phase power. The Fanuc control
uses a 3 phase xmfr to condition the voltage for the control circuits
and of course that power is rectified but it looks like the servo amps
use 3 phase directly.

I know that the Bridgeport BOSS-3 (and at least through BOSS-6)
used three phase to power the steppers -- but used a single phase for
each stepper. A big three phase transformer to provide the voltages for
the stepper drivers, with a "mag amp" (saturable reactor) to reduce the
voltage when the stepper was stopped or moving slowly, to avoid the
motor overheating. (The idea of a constant current supply to the
stepper had either not yet occurred (1975), or it was too complex for
affordable electronics at the time.) But, if you had enough current
available from single a phase, and replaced that three phase transformer
with one large single phase one, or three smaller ones (depending on
what was available) you could happily run that from single phase. Then
you would only need three phase for the spindle motor, and today a VFD
is the way of choice for driving a single motor.

BTW Running that from a rotary converter increases the chances of
blowing the transistors used to drive the stepper. They were
2N3055 transistors, nominally rated for 60 or 80 VDC. The ones
which I pulled from the old electronics on my Bridgeport test
out on a curve tracer to something on the order of 120 to 180
VCE max. I suspect that they were selected for the higher
breakdown voltage. Anyway -- with the nominal 80V being applied
at full speed to the steppers, and with an unbalance from a
rotary converter, it would be very easy to over-voltage the
transistors at their normal rating. (Of course, I pulled the
stepper motors and replaced them with DC servo motors, and was
pretty close to being ready to add the computer and LinuxCNC to
put it back in service when the lubricator set it all on fire,
keeping me out of the shop until it is cleaned up (a liter of
Vactra No. 2 makes a *lot* of dark sooty smoke, and a *lot* of
heat, too. :-(

Of course somewhere in the amp the ac gets
rectified.

Of course -- and once it is DC -- who cares how many phases were
used to produce it. :-)

The spindle drive will only accept 3 phase power.

The VFD? Others are available, of course. It sounds like you
have a particularly large one, however, so a VFD which will accept
single phase would be rather expensive, unless you were really lucky. I
have (or perhaps had? I haven't been able to test it, and the case is
partially melted) one which was good for 30A input and output at 240
VAC, and it would quite happily run from single phase. This comes up to
just short of 10 HP using single phase ratings. A bit over 15 HP with
three phase power input, I believe. It was all of $100.00 at a hamfest
in the mid 1990s IIRC.

There is
no braking resistor option either. Looking at the manual it says that
the power is dumped back into the 3 phase source.

One which is nice in terms of the power bill (how many HP *is*
that spindle motor?), but which complicates things with a rotary
converter, as others have mentioned. No real bets on what will work or
not.

If I do use 3 buck
xmfrs to lower the voltage will the xmfrs themselves be able to absorb
enough energy to be useful in that regard?

They will try to dump it back into the rotary converter.

Or will their only
advantage be the lower voltage? The xmfrs that Paul Drahn offered to
me will drop the voltage 20 volts. This is fine according to the
manual. When set at the 230 volt setting the drive will operate all
the way down to 198 volts.

That sounds worth trying -- especially at the price.
(Depends on how far you have to drive to get them, of course. :-)

Did he have a current rating on the secondary?

You are getting your three phase from a rotary converter. Is it
wired to give you a Wye "Y" neutral point, or is it delta? I think that
for the buck-boost, you really want Wye to simplify the setup. Delta
would need isolation transformer in each phase as well. If you
connected the primarys to a delta source, and hooked the secondarys
between the corners of the delta and the load you would be applying
correction voltages at a weird phase relationship to the voltages at the
corners. But if you have your rotary converter using a Wye connection
in the idler motor, you should be fine.

Good Luck,
DoN.
The phase converter output is wired Wye. The spindle motor is 15 HP.
And some jobs peg the load meter at 120%. Just briefly. The chips
coming off sound like hail hitting the inside of the lathe.
Eric

On 2012-10-28, wrote:
On 28 Oct 2012 02:17:43 GMT, "DoN. Nichols"
wrote:


[ ... ]

You are getting your three phase from a rotary converter. Is it
wired to give you a Wye "Y" neutral point, or is it delta? I think that
for the buck-boost, you really want Wye to simplify the setup. Delta
would need isolation transformer in each phase as well. If you
connected the primarys to a delta source, and hooked the secondarys
between the corners of the delta and the load you would be applying
correction voltages at a weird phase relationship to the voltages at the
corners. But if you have your rotary converter using a Wye connection
in the idler motor, you should be fine.

The phase converter output is wired Wye. The spindle motor is 15 HP.
And some jobs peg the load meter at 120%. Just briefly.

Wye -- good! That makes the buck-boost easier to set up.

O.K. 15 HP *That* is impressive.

The chips
coming off sound like hail hitting the inside of the lathe.

Make sure that the interlock on the door is good. :-)

I'm not sure when I will lose connection -- but the way they are
talking, we should have a significant period without power, so don't be
surprised if I stop posting in the next few days. (Just to the west of
the Washington DC Beltway in Virginia, and lots of rain and wind
promised. :-(

Good luck,
DoN.

--
Remove oil spill source from e-mail
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 10/27/2012 4:03 PM, wrote:
On Sat, 27 Oct 2012 12:55:01 -0700, Paul Drahn
wrote:

On 10/27/2012 10:36 AM, wrote:
On Fri, 26 Oct 2012 19:28:54 -0700, Paul Drahn
wrote:

On 10/26/2012 6:35 PM, wrote:
Greetings all you AC Electrical Types,
My shop is supplied with single phase juice (notice my proper use of
technical terms) at 245 volts average. The voltage does vary a little,
usually about 2 volts either way, but sometimes as high as 250 volts.
I've never seen it drop below 240, but then I don't monitor it 24/7. I
have just checked it many times over the years. I'm in a rural area
near the beginning of a line that serves many homes so maybe that has
something to do with it. Anyway, I use a rotary phase converter to
supply 3 phase power to my CNC machines. Setting the xmfr taps in the
machines allows me to supply the machines with power that is within
specs. Except for the Miyano lathe. It has xmfr taps for the Fanuc
control but not for the VFD spindle drive. The Fuji spindle drive has
a switch that allows for either 200 VAC or 220/230 VAC operation. So I
am supplying the spindle drive with voltage that is too high. And the
problem with that is when the spindle decelerates the spindle load
meter goes above 120%, the spindle drive shuts down, and sets an
"overvoltage" alarm. The drive uses regenerative braking and the
power supply must be capable of supplying 22kVa, according to this
link:
http://www.fujielectric.com/company/...3-108-1985.pdf
Anyway, after such a long winded description I'm wondering if I could
use 3 xmfrs buck configured to supply power to just the spindle drive.
I don't know what effect, if any, the regenerative braking would have
on any xmfrs connected between the rotary phase converter and the
spindle drive. If I can use buck xmfrs I need to know what xmfrs I can
use and how to wire them. Thanks for reading this far.
Eric
If you ever get to Central Oregon (Redmond), I will give you three
buck/boost transformers that will work for you. I will have to check the
voltage, but I think it is 20 volt buck/boost. They were part of an old
wave solder machine. I can give you the exact spec if interested. I
would love to get rid of them.

Paul
Greetings Paul,
I would drive down to Redmond to get those. I have a friend who lives
in Portland so maybe I could visit with him. Weekends would be best
for me but I could drive down on a weekday. Before I plan the trip it
would be best to have the specs so that I know they will work. How big
and heavy are these things?
Thanks,
Eric
I will be at the plant Monday evening and will get all the specs then.

Paul
Thanks Paul. I'm hoping your xmfrs will solve my problem.
Eric
Now at the plant to make two people working the second shift. Hope this
is the last week!

The transformers a
Square D Cat. # 1.5S46F, 1.5KVA, 115C temp rise.

HV: 240 or 120
LV 32 or 16.

Each weighs 35.5 lbs. Three transformers.

I will send a private email with pictures.

Paul