Ignoramus9179 wrote:

I built a self starting phase converter with a 10 HP idler and two 92
mF capacitors. It works great and starts in under 2 seconds.

I also have a very similar looking Century 7.5HP motor. They 10 HP and
7.5 HP look similar.

This 7.5 HP motor would NOT spin up from two other capacitors. If I
wire it with three capacitors (I have 5 total, 2 already used in the
main phase converter), it would spin up, but it takes it about 5
seconds to do so and it warms up appreciably. What gives?

Another tidbit is that the 7.5 HP motor starts just fine from 3 phase
output of my phase converter. I do not think that it is a bad
motor. Maybe some caps out of these three are in bad condition.

i

The inductance of the winding is different. The motor works.
Different caps than those used would work.

That is why the caps are approx and to adjust...

Remember, "we" are finding a way to get around the normal ways.
Different motors don't have to have the same specs, just have the power
and voltage ratings listed on the plate.

Martin

--
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

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Ignoramus9179 wrote:
I built a self starting phase converter with a 10 HP idler and two 92
mF capacitors. It works great and starts in under 2 seconds.

I also have a very similar looking Century 7.5HP motor. They 10 HP and
7.5 HP look similar.

This 7.5 HP motor would NOT spin up from two other capacitors. If I
wire it with three capacitors (I have 5 total, 2 already used in the
main phase converter), it would spin up, but it takes it about 5
seconds to do so and it warms up appreciably. What gives?

Another tidbit is that the 7.5 HP motor starts just fine from 3 phase
output of my phase converter. I do not think that it is a bad
motor. Maybe some caps out of these three are in bad condition.

Larger, older-style motors operate at a lower flux density and need more
capacitance per horsepower than modern TEFC motors. But you say the
motors are similar in design?

From my experience an unloaded motor will spin up with a wide range of
capacitor values. I would expect a 7.5 hp motor to spin up with a single
92 uF capacitor.

In what arrangement are you connecting the capacitors? If you're
connecting them in parallel, I reckon you most likely have two bad
capacitors or a motor with a dodgy connection somewhere.

Best wishes,

Chris

In article ,
Ignoramus9179 wrote:
I built a self starting phase converter with a 10 HP idler and two 92
mF capacitors. It works great and starts in under 2 seconds.

I also have a very similar looking Century 7.5HP motor. They 10 HP and
7.5 HP look similar.

This 7.5 HP motor would NOT spin up from two other capacitors. If I
wire it with three capacitors (I have 5 total, 2 already used in the
main phase converter), it would spin up, but it takes it about 5
seconds to do so and it warms up appreciably. What gives?

What is the RPM of the idler which you are using, and the motor
which you are *trying* to use? You may need a different capacitance for
a different RPM motor.

Another tidbit is that the 7.5 HP motor starts just fine from 3 phase
output of my phase converter. I do not think that it is a bad
motor. Maybe some caps out of these three are in bad condition.

Or -- you just may need more of them.

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 ---

i

You might view this as a good time to experiment with a different method
of spinning an idler.
A "new in the box" electrolytic capacitor will cost about $15. That'll
buy you a 250 mic capacitor that'll spin-up a good 7 1/2 HP idler in less
than a second.

Jerry




"Ignoramus9179" wrote in message
.. .
On 16 Aug 2005 02:10:55 -0400, DoN. Nichols wrote:
In article ,
Ignoramus9179 wrote:
I built a self starting phase converter with a 10 HP idler and two 92
mF capacitors. It works great and starts in under 2 seconds.

I also have a very similar looking Century 7.5HP motor. They 10 HP and
7.5 HP look similar.

This 7.5 HP motor would NOT spin up from two other capacitors. If I
wire it with three capacitors (I have 5 total, 2 already used in the
main phase converter), it would spin up, but it takes it about 5
seconds to do so and it warms up appreciably. What gives?

What is the RPM of the idler which you are using, and the motor
which you are *trying* to use? You may need a different capacitance for
a different RPM motor.

both my current 10 hp idler and 7.5 hp idler are 1750 or so rpm.

Another tidbit is that the 7.5 HP motor starts just fine from 3 phase
output of my phase converter. I do not think that it is a bad
motor. Maybe some caps out of these three are in bad condition.

Or -- you just may need more of them.

could be, but why can I get with 2 caps for my 10 HP RPC?

i

On Tue, 16 Aug 2005 02:41:46 GMT, Ignoramus9179
wrote:

I built a self starting phase converter with a 10 HP idler and two 92
mF capacitors. It works great and starts in under 2 seconds.

I also have a very similar looking Century 7.5HP motor. They 10 HP and
7.5 HP look similar.

This 7.5 HP motor would NOT spin up from two other capacitors. If I
wire it with three capacitors (I have 5 total, 2 already used in the
main phase converter), it would spin up, but it takes it about 5
seconds to do so and it warms up appreciably. What gives?

Another tidbit is that the 7.5 HP motor starts just fine from 3 phase
output of my phase converter. I do not think that it is a bad
motor. Maybe some caps out of these three are in bad condition.

i


The minimum single phase starting capacitor value can vary a
lot between OK motors of similar HP but different design. This is
a parameter of pretty well zero significance in three phase motor
design so there's no incentive to control or to reduce it.

Older motors using poorer performance iron tend to need
rather more capacitance. Another factor is the initial bearing
friction and, to a lesser extent, armature inertia. The heat
input to the motor is disproportionately large at very low speeds
- just an extra second at near stall can make a big difference.

There's probably nothing wrong with your 7.5 HP setup but
if you're worried about the capacitors try the following test.

. Connect the capacitor in series with a high wattage lamp (100W
or more) across 110v supply WITH CAPACITOR INITIALLY SHORTED OUT
then remove the short.

No change in brightness or nil brightness - dud capacitor

Reduced brightness - functioning capacitor - compare
the brightness with a ditto test on a similar value capacitor.

Jim

"Ignoramus23305" wrote in message
. ..
On Tue, 16 Aug 2005 12:27:08 GMT, Jerry Martes
wrote:

i

You might view this as a good time to experiment with a different
method
of spinning an idler.
A "new in the box" electrolytic capacitor will cost about $15. That'll
buy you a 250 mic capacitor that'll spin-up a good 7 1/2 HP idler in less
than a second.

I definitely like this suggestion. Experimenting with this stuff is
fun. What method would you suggest for turning that capacitor off
after the motor spins up?

i

I

My personal favorite method of spinning up an idler is to momentarily
connect the capacitor from one of the 220 lines to the "unfed winding" using
a solid state switch. The switches cost $12 at Marlin P, Jones.
Any big relay can be used to momentarily connect the capacitor, There is
a high degree of arcing associated with disconnecting the capacitor, so
'oversized' realys are desired.

Once the idler is spinning, and the tool motor is connected and loaded,
there is very little benefit derived as result of having the tuning
capacitor. It is my contention that "tuning" of the RPC is best left for
the experts to do. I'd advise that any RPC should be "tuned" only after it
is determined that there is a need.

Jerry

Jerry sez:
" My personal favorite method of spinning up an idler is to momentarily
connect the capacitor from one of the 220 lines to the "unfed winding"
using a solid state switch. The switches cost $12 at Marlin P, Jones.
Any big relay can be used to momentarily connect the capacitor, There
is a high degree of arcing associated with disconnecting the capacitor, so
'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched capacitor"
rotary phase converters such as the Booster brand seen on Metal Web News.

Bob Swinney



"Jerry Martes" wrote in message
news:uhoMe.6639$Al5.1944@trnddc04...

"Ignoramus23305" wrote in message
. ..
On Tue, 16 Aug 2005 12:27:08 GMT, Jerry Martes
wrote:

i

You might view this as a good time to experiment with a different
method
of spinning an idler.
A "new in the box" electrolytic capacitor will cost about $15.
That'll
buy you a 250 mic capacitor that'll spin-up a good 7 1/2 HP idler in
less
than a second.

I definitely like this suggestion. Experimenting with this stuff is
fun. What method would you suggest for turning that capacitor off
after the motor spins up?

i

I


Once the idler is spinning, and the tool motor is connected and loaded,
there is very little benefit derived as result of having the tuning
capacitor. It is my contention that "tuning" of the RPC is best left for
the experts to do. I'd advise that any RPC should be "tuned" only after
it is determined that there is a need.

Jerry

"Robert Swinney" wrote in message
...
Jerry sez:
" My personal favorite method of spinning up an idler is to momentarily
connect the capacitor from one of the 220 lines to the "unfed winding"
using a solid state switch. The switches cost $12 at Marlin P, Jones.
Any big relay can be used to momentarily connect the capacitor, There
is a high degree of arcing associated with disconnecting the capacitor,
so 'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched capacitor"
rotary phase converters such as the Booster brand seen on Metal Web News.

Bob Swinney


Yeah, Bob, the solid state relays do switch out the capacitor at zero
crossing. That is what makes them so interesting. No arcs. In
addition, the solid state relays can be controlled with 9 VDC. I use a
small alkaline battery, so no high voltage is troublesome around the ON-OFF
butons.

Jerry

Iggy sez: "I am quite interested, do you know of a web address where I
could see
these switches?"

How about it, Jerry? Is there a web site that you know of? What are some
of the exact specs; and are they available from some of the chip houses,
National, maybe?

Bob Swinney





"Ignoramus23305" wrote in message
...
On Wed, 17 Aug 2005 01:20:27 GMT, Jerry Martes
wrote:




"Robert Swinney" wrote in message
...
Jerry sez:
" My personal favorite method of spinning up an idler is to
momentarily
connect the capacitor from one of the 220 lines to the "unfed winding"
using a solid state switch. The switches cost $12 at Marlin P, Jones.
Any big relay can be used to momentarily connect the capacitor,
There
is a high degree of arcing associated with disconnecting the capacitor,
so 'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched capacitor"
rotary phase converters such as the Booster brand seen on Metal Web
News.

Bob Swinney




thanks

i

Ignoramus9179 wrote:

On Mon, 15 Aug 2005 22:30:24 -0500, Martin H. Eastburn wrote:

Ignoramus9179 wrote:


I built a self starting phase converter with a 10 HP idler and two 92
mF capacitors. It works great and starts in under 2 seconds.

I also have a very similar looking Century 7.5HP motor. They 10 HP and
7.5 HP look similar.

This 7.5 HP motor would NOT spin up from two other capacitors. If I
wire it with three capacitors (I have 5 total, 2 already used in the
main phase converter), it would spin up, but it takes it about 5
seconds to do so and it warms up appreciably. What gives?

Another tidbit is that the 7.5 HP motor starts just fine from 3 phase
output of my phase converter. I do not think that it is a bad
motor. Maybe some caps out of these three are in bad condition.

i


The inductance of the winding is different. The motor works.
Different caps than those used would work.


Do you mean different, as in having different capacitance?

i

The caps are trying to counteract the winding inductance.
So if the motor changes between models, companies, Years then the inductance
is either the same, lower or higher. One in three you have to change the cap value.

It is the same for a larger or smaller motor. (also naturally)

Martin

--
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

Bob

I had already stocked up on the solid state switches at All Electronics
while they had hundreds of "take outs" at about $2.00 each. I dont see any
in the most recent All Electronics (www.allelectronics.com) catalog. Marlin
P. Jones (www.mpja.com) shows some 25 amp, 280 VAC solid state switches at
$11.95 each.

Jerry



"Robert Swinney" wrote in message
...
Iggy sez: "I am quite interested, do you know of a web address where I
could see
these switches?"

How about it, Jerry? Is there a web site that you know of? What are some
of the exact specs; and are they available from some of the chip houses,
National, maybe?

Bob Swinney





"Ignoramus23305" wrote in message
...
On Wed, 17 Aug 2005 01:20:27 GMT, Jerry Martes
wrote:




"Robert Swinney" wrote in message
...
Jerry sez:
" My personal favorite method of spinning up an idler is to
momentarily
connect the capacitor from one of the 220 lines to the "unfed winding"
using a solid state switch. The switches cost $12 at Marlin P,
Jones.
Any big relay can be used to momentarily connect the capacitor, There
is a high degree of arcing associated with disconnecting the
capacitor,
so 'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched capacitor"
rotary phase converters such as the Booster brand seen on Metal Web
News.

Bob Swinney




thanks

i

Thanx, Jerry! Hey, Iggy - take a look.

Bob Swinney

"Jerry Martes" wrote in message
news:STxMe.7521$Xw5.3803@trnddc02...

Bob

I had already stocked up on the solid state switches at All Electronics
while they had hundreds of "take outs" at about $2.00 each. I dont see
any in the most recent All Electronics (www.allelectronics.com) catalog.
Marlin P. Jones (www.mpja.com) shows some 25 amp, 280 VAC solid state
switches at $11.95 each.

Jerry



"Robert Swinney" wrote in message
...
Iggy sez: "I am quite interested, do you know of a web address where I
could see
these switches?"

How about it, Jerry? Is there a web site that you know of? What are
some of the exact specs; and are they available from some of the chip
houses, National, maybe?

Bob Swinney





"Ignoramus23305" wrote in message
...
On Wed, 17 Aug 2005 01:20:27 GMT, Jerry Martes
wrote:




"Robert Swinney" wrote in message
...
Jerry sez:
" My personal favorite method of spinning up an idler is to
momentarily
connect the capacitor from one of the 220 lines to the "unfed
winding"
using a solid state switch. The switches cost $12 at Marlin P,
Jones.
Any big relay can be used to momentarily connect the capacitor,
There
is a high degree of arcing associated with disconnecting the
capacitor,
so 'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched capacitor"
rotary phase converters such as the Booster brand seen on Metal Web
News.

Bob Swinney




thanks

i

Agreed! Try the cap testing idea given by another RCM poster.

Bob Swinney
"Ignoramus4384" wrote in message
.. .
On Wed, 17 Aug 2005 08:12:30 -0500, Robert Swinney
wrote:
Thanx, Jerry! Hey, Iggy - take a look.

Thanks, they are interesting. Using them would mean that I need to
also add some DC power supply to the converter. Anyway, I will give it
a serious thought. At this point, common sense suggests that the most
likely cause of the trouble is bad caps.

i

Bob Swinney

"Jerry Martes" wrote in message
news:STxMe.7521$Xw5.3803@trnddc02...

Bob

I had already stocked up on the solid state switches at All Electronics
while they had hundreds of "take outs" at about $2.00 each. I dont see
any in the most recent All Electronics (www.allelectronics.com) catalog.
Marlin P. Jones (www.mpja.com) shows some 25 amp, 280 VAC solid state
switches at $11.95 each.

Jerry



"Robert Swinney" wrote in message
...
Iggy sez: "I am quite interested, do you know of a web address where I
could see
these switches?"

How about it, Jerry? Is there a web site that you know of? What are
some of the exact specs; and are they available from some of the chip
houses, National, maybe?

Bob Swinney





"Ignoramus23305" wrote in message
...
On Wed, 17 Aug 2005 01:20:27 GMT, Jerry Martes
wrote:




"Robert Swinney" wrote in message
...
Jerry sez:
" My personal favorite method of spinning up an idler is to
momentarily
connect the capacitor from one of the 220 lines to the "unfed
winding"
using a solid state switch. The switches cost $12 at Marlin P,
Jones.
Any big relay can be used to momentarily connect the capacitor,
There
is a high degree of arcing associated with disconnecting the
capacitor,
so 'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched
capacitor"
rotary phase converters such as the Booster brand seen on Metal Web
News.

Bob Swinney




thanks

i









--

I

Think 9 volt "transistor battery". Thats enough DC for the solid state
switch I use. I told you about this several months ago. I know the
concept isnt too complex for you to have grasped. I think I have failed to
be sufficiently clear with my communications.
All thats needed ot build the RPC is a switch to connect the 220 single
phase to the idler, and a start button to momrntarily insert a capacitor
from the input single phase line to the unfed leg of the motor.
A rotary phase converter with a1 HP idler will normally spin up an
*unloaded* 10 HP tool motor. That 10 HP tool motor will perform equally
as well with that 1 HP idler as with true 3 phase whenever the tool is
loaded to 5 HP or less.

Jerry



"Ignoramus4384" wrote in message
.. .
On Wed, 17 Aug 2005 08:12:30 -0500, Robert Swinney
wrote:
Thanx, Jerry! Hey, Iggy - take a look.

Thanks, they are interesting. Using them would mean that I need to
also add some DC power supply to the converter. Anyway, I will give it
a serious thought. At this point, common sense suggests that the most
likely cause of the trouble is bad caps.

i

Bob Swinney

"Jerry Martes" wrote in message
news:STxMe.7521$Xw5.3803@trnddc02...

Bob

I had already stocked up on the solid state switches at All Electronics
while they had hundreds of "take outs" at about $2.00 each. I dont see
any in the most recent All Electronics (www.allelectronics.com) catalog.
Marlin P. Jones (www.mpja.com) shows some 25 amp, 280 VAC solid state
switches at $11.95 each.

Jerry



"Robert Swinney" wrote in message
...
Iggy sez: "I am quite interested, do you know of a web address where I
could see
these switches?"

How about it, Jerry? Is there a web site that you know of? What are
some of the exact specs; and are they available from some of the chip
houses, National, maybe?

Bob Swinney





"Ignoramus23305" wrote in message
...
On Wed, 17 Aug 2005 01:20:27 GMT, Jerry Martes
wrote:




"Robert Swinney" wrote in message
...
Jerry sez:
" My personal favorite method of spinning up an idler is to
momentarily
connect the capacitor from one of the 220 lines to the "unfed
winding"
using a solid state switch. The switches cost $12 at Marlin P,
Jones.
Any big relay can be used to momentarily connect the capacitor,
There
is a high degree of arcing associated with disconnecting the
capacitor,
so 'oversized' realys are desired."

Do these solid state switches operate at "zero crossing" time? I am
guessing they are similar to those used in high $ "switched
capacitor"
rotary phase converters such as the Booster brand seen on Metal Web
News.

Bob Swinney




thanks

i









--