I can't get my 5 horse horizontal spindle to start in the higher speeds...
It trips the 30 amp circuit breaker ahead of my RPC. If anybody remembers, I
asked about this issue a week ago, adding capacitors and larger idlers lets
it start in lower gears,but I'm not there yet. It uses very little power
once up to speed.

I looked at a VFD. The way the control panel is wired, it would be hard to
install. There is a rotary switch that flips two leads for reversing
rotation ahead of a motor contactor. Estop logic can drop this contactor.
There's start/stop pushbuttons on the operator panel for motor operation.
All logic uses 110 VAC.

Iggy suggested a soft start. see this example:
http://cgi.ebay.com/Siemens-Series-E...QQcmdZViewItem

I'd like to know how these things are wired in before dropping $100. Can a
soft start just be installed right in front of the motor? So if power comes
on the motor winds up slowly. Will it allow reverse rotation if two leads
are switched? Otherwise, I'll look for a VFD.

Karl

Karl Townsend wrote:

I can't get my 5 horse horizontal spindle to start in the higher speeds...
It trips the 30 amp circuit breaker ahead of my RPC. If anybody remembers, I
asked about this issue a week ago, adding capacitors and larger idlers lets
it start in lower gears,but I'm not there yet. It uses very little power
once up to speed.

I looked at a VFD. The way the control panel is wired, it would be hard to
install. There is a rotary switch that flips two leads for reversing
rotation ahead of a motor contactor. Estop logic can drop this contactor.
There's start/stop pushbuttons on the operator panel for motor operation.
All logic uses 110 VAC.

Nothing you mentioned there would make it difficult to connect a VFD.
Start and stop pushbuttons simply get disconnected from the existing
connections and wired to the VFD. Need more detail on the rotary
reversing switch, but it should be able to be wired to the VFD as well.

Can you post a link to a schematic so we can give you a rewiring
diagram?

Robert Swinney wrote:

Sorry but my post re. subject was incorrect: The idler motor HP should be at least 1-1/2 times that
of the load motor. That implies an idler motor of at least 7.5 HP and combined HP of 12.5.

I also noted in a previous thread to try starting the vertical spindle
first to let that add another 5hp worth of idler to the converter before
trying to start the apparently high inertia horizontle spindle.

A proper VFD will entirely eliminate the problems he's having, can
eliminate the noisy RPC and if done properly a single VFD can operate
either of the spindles.

On 2008-06-13, Pete C. wrote:

Robert Swinney wrote:

Sorry but my post re. subject was incorrect: The idler motor HP should be at least 1-1/2 times that
of the load motor. That implies an idler motor of at least 7.5 HP and combined HP of 12.5.

I also noted in a previous thread to try starting the vertical spindle
first to let that add another 5hp worth of idler to the converter before
trying to start the apparently high inertia horizontle spindle.

A proper VFD will entirely eliminate the problems he's having, can
eliminate the noisy RPC and if done properly a single VFD can operate
either of the spindles.

By the way... How is your VFD working for you? Did you add a switch or
you just use the panel buttons?
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Ignoramus29659 wrote:

On 2008-06-13, Pete C. wrote:

Robert Swinney wrote:

Sorry but my post re. subject was incorrect: The idler motor HP should be at least 1-1/2 times that
of the load motor. That implies an idler motor of at least 7.5 HP and combined HP of 12.5.

I also noted in a previous thread to try starting the vertical spindle
first to let that add another 5hp worth of idler to the converter before
trying to start the apparently high inertia horizontle spindle.

A proper VFD will entirely eliminate the problems he's having, can
eliminate the noisy RPC and if done properly a single VFD can operate
either of the spindles.

By the way... How is your VFD working for you? Did you add a switch or
you just use the panel buttons?

I've been a bit busy since getting back from my dive trip, so the VFD is
still sitting on the end of the Bridgeport table hooked up for testing.
I did power it up again and play stepping around various frequencies and
it still works nicely. I may get to work on it this weekend, before I
have to run out of town on a work trip to Chicago for a few days.

Bob brings up the point about the breaker "should" hold. If the breaker
has been tripped multiple times, it may be aging enough to lower the
time delay. Might work better with a new breaker.

Robert Swinney wrote:
A schematic of your RPC would be helpful. Although a RPC is not a "soft start" per se; an
appropriately sized RPC and load combination will start fast enough so that the breaker doesn't
have time enough to trip. The idler motor, capacitors, and load motor comprise an electrical
network in which total current circulates. A proper RPC will have an idler motor at least 1-1/2
times the HP rating of the load motor and sufficient capacitance during the starting interval to
bring the load motor up to speed in about 1/2 second. Generally speaking, if wiring and breaker are
correctly sized, the surge starting current of the RPC and load combination will be over before the
breaker has had time to trip. A 3 HP idler motor and 5 HP load should be wired and breaker-sized
for at least 25 amps. Suggest you speak with a local electrician to maintain code.

Bob (never did get my sack of apples) Swinney










"Karl Townsend" wrote in message
ews.com...
I can't get my 5 horse horizontal spindle to start in the higher speeds...
It trips the 30 amp circuit breaker ahead of my RPC. If anybody remembers, I
asked about this issue a week ago, adding capacitors and larger idlers lets
it start in lower gears,but I'm not there yet. It uses very little power
once up to speed.

I looked at a VFD. The way the control panel is wired, it would be hard to
install. There is a rotary switch that flips two leads for reversing
rotation ahead of a motor contactor. Estop logic can drop this contactor.
There's start/stop pushbuttons on the operator panel for motor operation.
All logic uses 110 VAC.

Iggy suggested a soft start. see this example:
http://cgi.ebay.com/Siemens-Series-E...QQcmdZViewItem

I'd like to know how these things are wired in before dropping $100. Can a
soft start just be installed right in front of the motor? So if power comes
on the motor winds up slowly. Will it allow reverse rotation if two leads
are switched? Otherwise, I'll look for a VFD.

Karl

A schematic of your RPC would be helpful. Although a RPC is not a "soft
start" per se; an

My question is about a soft start. Do you or Pete know anything about them?


Adding more idlers didn't work. i can start other 5 hp motors, i.e. the main
spindle. This one has a ton of gears to bring up to speed - too
much start load.

I can handle wiring a VFD. I don't want to tear into the existing control.
In particualar, I don't like the idea of mixing 24 Volt VFD logic on the
same switches that have 110 power for everything else. There's already two
lbs. of junk in a one lb. box. on the control panel. Not room for separate
stuff.



Karl

Karl Townsend wrote:

A schematic of your RPC would be helpful. Although a RPC is not a "soft
start" per se; an

My question is about a soft start. Do you or Pete know anything about them?

Adding more idlers didn't work. i can start other 5 hp motors, i.e. the main
spindle. This one has a ton of gears to bring up to speed - too
much start load.

I can handle wiring a VFD. I don't want to tear into the existing control.
In particualar, I don't like the idea of mixing 24 Volt VFD logic on the
same switches that have 110 power for everything else. There's already two
lbs. of junk in a one lb. box. on the control panel. Not room for separate
stuff.

Karl

Don't know much about the "soft start", it appears to pretty much be a
"VFD lite" and you could do the same with a VFD configured to start when
input power was applied.

You wouldn't ever be mixing 110VAC and 24VDC on the same switch the
former 110VAC switches just become 24VDC logic level inputs to the VFD.
Most of the 110VAC would be eliminated, or even all of it. What exactly
is there anyway, I thought just controls for two 5hp spindles and an
E-stop.

Make that November / December 2001 Ed. of Homeshop Machinist. The article
also appears in Metal Web
News along with a lot of others....

And a very fine article it was too. I remember reading it when it came out.
But, IIRC, not a dang thing in it about soft start devices.

Karl

Karl Townsend wrote:

Make that November / December 2001 Ed. of Homeshop Machinist. The article
also appears in Metal Web
News along with a lot of others....

And a very fine article it was too. I remember reading it when it came out.
But, IIRC, not a dang thing in it about soft start devices.

Karl

I think his point is that a properly setup RPC will start even the worst
loads.

Possibly a dumb question, but have you actually got the thing running in
that upper gear and confirmed that there isn't something binding?

On 2008-06-13, Karl Townsend wrote:
I can't get my 5 horse horizontal spindle to start in the higher speeds...
It trips the 30 amp circuit breaker ahead of my RPC. If anybody remembers, I
asked about this issue a week ago, adding capacitors and larger idlers lets
it start in lower gears,but I'm not there yet. It uses very little power
once up to speed.

I looked at a VFD. The way the control panel is wired, it would be hard to
install. There is a rotary switch that flips two leads for reversing
rotation ahead of a motor contactor. Estop logic can drop this contactor.

That is no problem -- you feed the motor directly from the VFD,
and use a selected three of the four terminals which flip the two leads
to select forward or reverse command to the VFD (dropping to 5V logic
commands instead of the 115 V ones which are currently in use.

There's start/stop pushbuttons on the operator panel for motor operation.

Most VFDs have the ability to accept the start/stop pushbuttons
(working at 5V) without problems.

All logic uses 110 VAC.

Not necessary (nor desirable) with the VFD. I'm sure that you
would feel more comfortable re-wiring the panel at 5V instead of 110 V.

Iggy suggested a soft start. see this example:
http://cgi.ebay.com/Siemens-Series-E...QQcmdZViewItem

That might do well.

I'd like to know how these things are wired in before dropping $100. Can a
soft start just be installed right in front of the motor? So if power comes
on the motor winds up slowly. Will it allow reverse rotation if two leads
are switched? Otherwise, I'll look for a VFD.

There, I can't help you, since I've never worked with one of
these. Perhaps go to the maker's site and download the manual if
possible?

Good Luck,
DoN.

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