I'm starting to work on "the kid's" Xmas present. A mulit stage RPC
with 50 hp. of idlers. I'll most likely use a 10 hp for startup and
then optionally bring in one or two more 20hp. depending on what's
running.

At some point (next spring?) I'll give him the 20hp mazak M4 lathe
that doesn't start well in higher gears. Maybe a beefier RPC will
help.

Anyway, I just came accross this thread:
http://www.cnczone.com/forums/showthread.php?t=110991

Anyone know about controllers for load on an RPC?

Or, anybody worked with bringing in caps during a large motor start?
Other ideas? Starting the mazak dims the lights on the whole place
and drops the rpm of the phase converter.

Karl

"Karl Townsend" wrote in message
...
I'm starting to work on "the kid's" Xmas present. A mulit stage RPC
with 50 hp. of idlers. I'll most likely use a 10 hp for startup and
then optionally bring in one or two more 20hp. depending on what's
running.

At some point (next spring?) I'll give him the 20hp mazak M4 lathe
that doesn't start well in higher gears. Maybe a beefier RPC will
help.

Anyway, I just came accross this thread:
http://www.cnczone.com/forums/showthread.php?t=110991

Anyone know about controllers for load on an RPC?

Or, anybody worked with bringing in caps during a large motor start?
Other ideas? Starting the mazak dims the lights on the whole place
and drops the rpm of the phase converter.

Karl

What kind/capacity of electrical service does he have?

On Sat, 28 Aug 2010 19:30:15 -0400, "ATP"
wrote:


"Karl Townsend" wrote in message
.. .
I'm starting to work on "the kid's" Xmas present. A mulit stage RPC
with 50 hp. of idlers. I'll most likely use a 10 hp for startup and
then optionally bring in one or two more 20hp. depending on what's
running.

At some point (next spring?) I'll give him the 20hp mazak M4 lathe
that doesn't start well in higher gears. Maybe a beefier RPC will
help.

Anyway, I just came accross this thread:
http://www.cnczone.com/forums/showthread.php?t=110991

Anyone know about controllers for load on an RPC?

Or, anybody worked with bringing in caps during a large motor start?
Other ideas? Starting the mazak dims the lights on the whole place
and drops the rpm of the phase converter.

Karl

What kind/capacity of electrical service does he have?

200 amp 1 phase 240 volt. standard residential. Just like mine.

karl

On 2010-08-28, Karl Townsend wrote:
On Sat, 28 Aug 2010 19:30:15 -0400, "ATP"
wrote:


"Karl Townsend" wrote in message
. ..
I'm starting to work on "the kid's" Xmas present. A mulit stage RPC
with 50 hp. of idlers. I'll most likely use a 10 hp for startup and
then optionally bring in one or two more 20hp. depending on what's
running.

At some point (next spring?) I'll give him the 20hp mazak M4 lathe
that doesn't start well in higher gears. Maybe a beefier RPC will
help.

Anyway, I just came accross this thread:
http://www.cnczone.com/forums/showthread.php?t=110991

Anyone know about controllers for load on an RPC?

Or, anybody worked with bringing in caps during a large motor start?
Other ideas? Starting the mazak dims the lights on the whole place
and drops the rpm of the phase converter.

Karl

What kind/capacity of electrical service does he have?

200 amp 1 phase 240 volt. standard residential. Just like mine.

karl


Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.

i

Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.

You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

karl

"Karl Townsend" wrote in message
...
On Sat, 28 Aug 2010 19:30:15 -0400, "ATP"
wrote:


"Karl Townsend" wrote in message
. ..
I'm starting to work on "the kid's" Xmas present. A mulit stage RPC
with 50 hp. of idlers. I'll most likely use a 10 hp for startup and
then optionally bring in one or two more 20hp. depending on what's
running.

At some point (next spring?) I'll give him the 20hp mazak M4 lathe
that doesn't start well in higher gears. Maybe a beefier RPC will
help.

Anyway, I just came accross this thread:
http://www.cnczone.com/forums/showthread.php?t=110991

Anyone know about controllers for load on an RPC?

Or, anybody worked with bringing in caps during a large motor start?
Other ideas? Starting the mazak dims the lights on the whole place
and drops the rpm of the phase converter.

Karl

What kind/capacity of electrical service does he have?

200 amp 1 phase 240 volt. standard residential. Just like mine.

karl

That's going to be a huge load to place on a residential service. I know you
aren't going to be running 50 hp at full load but even 20 times let's say
800 watts at 240 is over 66 amps? I'd be checking with an amprobe and making
sure all the connections are perfect and don't get hot. Not impossible but a
little unusual so proceed with caution, especially if there are subpanels
and long runs involved. I've seen a fair amount of large stab-on breakers
heat up and burn the stab on the bus.

Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions. The power company guys have some kind of special relays
that bring
in the additional caps without directly connecting them together, so
there are no
huge currents between them. If you use standard contactors, there will
be huge
sparks when the contacts close, as the capacitors will be charged to
different voltages at
that instant, and so currents of thousands of amps (I'm not kidding, here)
will flow for some microseconds. It may be possible to control this
with small resistances
of a few Ohms in series with the cap bank. The resistors will hinder
the functioning of the
capacitors, though.

Running a 20 Hp idler motor PLUS a 20 Hp spindle motor off a 200 A
residential service
sounds like big trouble. The power draw assuming perfect power factor
isn't that huge,
but idler motors tend to have TERRIBLE power factor. A PF correction
capacitor bank will
help a lot. But, the current demand when the motors start is going to
be horrendous.
The full load current on 3-phase 240 V for a 20 Hp motor is about 66 A.
I don't know
what the line current of an RPC plus a 20 Hp motor is on 240
single-phase, but it is
going to be a lot higher, possibly over 100 A.
I would think it makes a lot more sense to get a VFD, then you get an
adjustable amount
of slow-start, and can keep from dimming all the lights in the
neighborhood. With all these
idler motors, cap banks, relays and control circuits, you could likely
have paid for a good used
VFD by now.

Jon

On 2010-08-29, Jon Elson wrote:
Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions.

What about zero crossing solid state relays?

Running a 20 Hp idler motor PLUS a 20 Hp spindle motor off a 200 A
residential service sounds like big trouble. The power draw
assuming perfect power factor isn't that huge, but idler motors tend
to have TERRIBLE power factor. A PF correction capacitor bank will
help a lot. But, the current demand when the motors start is going
to be horrendous.

Just to give you guys a data point. I have a RPC with two idlers, 10
and 7.5 HP.

When I start the 10 HP one, it takes somewhat under a second, and the
current draw is 120 amps. It does not dim lights in my house. Starting
the 7.5 HP idler is near instantaneous, "pop" and it is running.

The full load current on 3-phase 240 V for a 20 Hp motor is about 66
A. I don't know what the line current of an RPC plus a 20 Hp motor
is on 240 single-phase, but it is going to be a lot higher, possibly
over 100 A. I would think it makes a lot more sense to get a VFD,
then you get an adjustable amount of slow-start, and can keep from
dimming all the lights in the neighborhood. With all these idler
motors, cap banks, relays and control circuits, you could likely
have paid for a good used VFD by now.

They have soft starts on ebay pretty cheaply, this may be the ticket
for Karl if he can get spindle-at-speed signal work correctly.

If Karl's spindle motor is a regular motor, maybe he can get a smaller
one.

Mazak should tell Karl what wiring etc is needed to hook this up, so
we can see if the statring current is manageable. I would call Mazak.

i

On Sat, 28 Aug 2010 22:56:56 -0500, Jon Elson
wrote:

Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions. The power company guys have some kind of special relays
that bring
in the additional caps without directly connecting them together, so
there are no
huge currents between them. If you use standard contactors, there will
be huge
sparks when the contacts close, as the capacitors will be charged to
different voltages at
that instant, and so currents of thousands of amps (I'm not kidding, here)
will flow for some microseconds. It may be possible to control this
with small resistances
of a few Ohms in series with the cap bank. The resistors will hinder
the functioning of the
capacitors, though.

Running a 20 Hp idler motor PLUS a 20 Hp spindle motor off a 200 A
residential service
sounds like big trouble. The power draw assuming perfect power factor
isn't that huge,
but idler motors tend to have TERRIBLE power factor. A PF correction
capacitor bank will
help a lot. But, the current demand when the motors start is going to
be horrendous.
The full load current on 3-phase 240 V for a 20 Hp motor is about 66 A.
I don't know
what the line current of an RPC plus a 20 Hp motor is on 240
single-phase, but it is
going to be a lot higher, possibly over 100 A.
I would think it makes a lot more sense to get a VFD, then you get an
adjustable amount
of slow-start, and can keep from dimming all the lights in the
neighborhood. With all these
idler motors, cap banks, relays and control circuits, you could likely
have paid for a good used
VFD by now.

Jon

I agree.

Gunner, running a Clausing 1500, with 7.5hp motor just hunky on a 5hp
rotary converter...as long as he starts the motor FIRST, before engaging
the spindle.



I am the Sword of my Family
and the Shield of my Nation.
If sent, I will crush everything you have built,
burn everything you love,
and kill every one of you.
(Hebrew quote)

On Sat, 28 Aug 2010 22:56:56 -0500, Jon Elson
wrote:

Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions.

??? I'm doing it now. My existing converter starts a 15 with run
caps, drops the start caps, then engages a 25 and a second bank of run
caps. hard to believe its impossible to switch in say 500 MFD of
additional capacitance on a running converter. But, I'm not the expert
here.

The system I'm planning is for an entire shop of three phase
equipment. I'm wanting to build the best possible system for many
years of use. A vfd might bve the best solution for the large lathe
but they are very expensive and the lathe works now, it just could be
better. Surely some incremental improvements are possible over the one
that's running today.

Karl

On Sun, 29 Aug 2010 06:05:35 -0500, Karl Townsend
wrote:

On Sat, 28 Aug 2010 22:56:56 -0500, Jon Elson
wrote:

Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions.

??? I'm doing it now. My existing converter starts a 15 with run
caps, drops the start caps, then engages a 25 and a second bank of run
caps. hard to believe its impossible to switch in say 500 MFD of
additional capacitance on a running converter. But, I'm not the expert
here.

The system I'm planning is for an entire shop of three phase
equipment. I'm wanting to build the best possible system for many
years of use. A vfd might bve the best solution for the large lathe
but they are very expensive and the lathe works now, it just could be
better. Surely some incremental improvements are possible over the one
that's running today.

Karl

I happen to have an 80 hp..yes...80 horsepower VFD at my disposal..if
anyone needs one.

It will be cheap too.

Gunner


I am the Sword of my Family
and the Shield of my Nation.
If sent, I will crush everything you have built,
burn everything you love,
and kill every one of you.
(Hebrew quote)

They have soft starts on ebay pretty cheaply, this may be the ticket
for Karl if he can get spindle-at-speed signal work correctly.

I spent some time looking. Can't seem to find 20hp. and 220 volt. They
are all for 440 in the higher horses. I did find a few rated 20hp at
440 and 10hp at 220. So, I looked at 40 hp. units. only a couple but
no mention of multivoltage and they are up in VFD price range.

I'll watch a while, do you know if all soft starts work on both 440
and 220?

I'm not sure soft starts or VFDs are the answer anyway. You drive this
lathe like an old truck. The manual says start in LO range (1-8) then
shift to HI(9-16). This takes to much load so we shift four gears at a
time till gear twelve then two at a time.


Anyway, the main subject here is how to build the best possible RPC
for the kid's new shop. The lathe is just the worst example.

karl





Karl

On Sun, 29 Aug 2010 04:23:38 -0700, Gunner Asch
wrote:

On Sun, 29 Aug 2010 06:05:35 -0500, Karl Townsend
wrote:

On Sat, 28 Aug 2010 22:56:56 -0500, Jon Elson
wrote:

Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions.

??? I'm doing it now. My existing converter starts a 15 with run
caps, drops the start caps, then engages a 25 and a second bank of run
caps. hard to believe its impossible to switch in say 500 MFD of
additional capacitance on a running converter. But, I'm not the expert
here.

The system I'm planning is for an entire shop of three phase
equipment. I'm wanting to build the best possible system for many
years of use. A vfd might bve the best solution for the large lathe
but they are very expensive and the lathe works now, it just could be
better. Surely some incremental improvements are possible over the one
that's running today.

Karl

I happen to have an 80 hp..yes...80 horsepower VFD at my disposal..if
anyone needs one.

It will be cheap too.

if its 220 volt, i need it. But me thinks no way is 80 hp 220 volt.

karl

On Sun, 29 Aug 2010 07:41:38 -0500, Karl Townsend
wrote:

On Sun, 29 Aug 2010 04:23:38 -0700, Gunner Asch
wrote:

On Sun, 29 Aug 2010 06:05:35 -0500, Karl Townsend
wrote:

On Sat, 28 Aug 2010 22:56:56 -0500, Jon Elson
wrote:

Karl Townsend wrote:
Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.

You can't switch additional capacitors into an existing cap bank without
massive
explosions.

??? I'm doing it now. My existing converter starts a 15 with run
caps, drops the start caps, then engages a 25 and a second bank of run
caps. hard to believe its impossible to switch in say 500 MFD of
additional capacitance on a running converter. But, I'm not the expert
here.

The system I'm planning is for an entire shop of three phase
equipment. I'm wanting to build the best possible system for many
years of use. A vfd might bve the best solution for the large lathe
but they are very expensive and the lathe works now, it just could be
better. Surely some incremental improvements are possible over the one
that's running today.

Karl

I happen to have an 80 hp..yes...80 horsepower VFD at my disposal..if
anyone needs one.

It will be cheap too.

if its 220 volt, i need it. But me thinks no way is 80 hp 220 volt.

karl

Im fairly certain it is indeed 220 volts. Ill check later in the day
when I wake up.

Ive been out tuning and tweaking the Clausing lathe I got running
yesterday. 14x52"

Im rather surprised that the 7.5hp motor runs nicely on the 5hp rotary
converter Ive got powering the shop. I just cant start the motor AND the
spindle at the same time. I have to fire up the drive motor, then use
the clutch to fire up the spindle. Which works for me. Carraige lock
bolt is busted down in the apron..got it out of the lock assembly..now I
just have to fish the stub out of the hole. Cant find any of the damned
..25 magnets I used to be swimming in. Shrug...Ill be up at noon-2pm and
will fish it out, and use the lathe to turn a new bolt, and the new
mill(s) to machine the head.

Crom its nice having decent machines finally.

Gunner


I am the Sword of my Family
and the Shield of my Nation.
If sent, I will crush everything you have built,
burn everything you love,
and kill every one of you.
(Hebrew quote)

Ignoramus5734 wrote:
On 2010-08-29, Jon Elson wrote:

Karl Townsend wrote:

Karl, your plan should work very well, it is easy to do also if you
have the electrical gear necessary, such as contactors.


You have more confidence than I. My RPC is essentially the same and
the lathe can't be started in the top four gears without blowing a
fuse. The idea of bringing in more caps during extreme load has me
intrigued.


You can't switch additional capacitors into an existing cap bank without
massive
explosions.


What about zero crossing solid state relays?

That might be the trick! Of course, if it ever fails to turn on right at
the zero crossing, the relay
will be history! But, that ought to work better than a big contactor,
which would have a really
short life.

Jon

Karl Townsend wrote:
On Sat, 28 Aug 2010 22:56:56 -0500, Jon Elson
wrote:



You can't switch additional capacitors into an existing cap bank without
massive
explosions.


??? I'm doing it now. My existing converter starts a 15 with run
caps, drops the start caps, then engages a 25 and a second bank of run
caps. hard to believe its impossible to switch in say 500 MFD of
additional capacitance on a running converter. But, I'm not the expert
here.

If these caps are wired to the generated leg of each idler, that may be
different.
Generally, though, connecting banks of capacitors together, if the
voltage in them is not the same,
leads to HUGE currents, in the thousands of amps, and will severely
damage a beefy contactor
even the first first time it is switched on. Putting sufficient
resistance in the circuit will reduce
that peak current, so maybe that is why it works for you.

Jon