Fitch,3ph,et al

Fitch,3ph,et al

Post by Lee Marshal » Thu, 19 Nov 1998 04:00:00



Wow! It really works!
I have been using a 7.5hp idler motor with just capacitor start for
several years and knew that the legs were not evenly balanced, but never
had any problem running my equipment.
The other day, I powered up a new hydraulic pump on a shop press, using
a 1.5hp single phase motor and it stalled the motor. "Well", says I,
"I've got a 5hp 3ph motor that I can use. No problem". After making the
mounting mod's, I fired it up, using the rotary converter, and would you
believe, it stalled the motor at just slightly higher pressure than the
1.5hp?
I dug out all of the 3ph stuff that has been floating around on the NG,
including info by Fitch, Hanrahan, Carlson, plus a lot of miscellaneous
stuff from all over. Went over to RA Enterprises in San Jose, dug
through their capacitor bins, and came up with an arm load of the darn
things for $25.00, plus a brand new 3ph motor contactor rated for 30hp
with 24vac/dc coil for $15.00. BTW, there are several more of these over
there, made by Fuji, still in the box with all hardware.
Hooked everything up and after first making the mistake of doing it in
series rather than parallel, got the unit up and running. Checked the
motor leads before adding the capacitors, and showed 10.5 on one, 10.0
on another and .8 on the manufactured leg. After adding the capacitors,
evenly matched on each side, I got readings of 7.5, 6.0, and 4.0
respectively. Finally, it took 40mf more on one leg to get the final
readings of: 6.0, 6.0, 5.5.
Probably the most interesting thing was the major decrease in amperage
from before the addition. Another was just how simple the entire thing
was. It simply took recognising the necessity and then doing it.

Thanks to all who have provided so much useful information on this and
other subjects.

Lee

 
 
 

Fitch,3ph,et al

Post by David Berryhil » Fri, 20 Nov 1998 04:00:00


............snip

Quote:

>Thanks to all who have provided so much useful information on this and
>other subjects.

>Lee

Hear, hear!!  I would also like to thank the many members of this group who
have taught me so much about 3 phase power!

Dave Berryhill

 
 
 

Fitch,3ph,et al

Post by Vince Iori » Fri, 20 Nov 1998 04:00:00


Quote:

> Wow! It really works!
> I have been using a 7.5hp idler motor with just capacitor start for
> several years and knew that the legs were not evenly balanced, but never
> had any problem running my equipment.

<Stuff deleted>

Lee,

  It's been a while since I got my converter up and running.  If I
remember correctly, when I have the amps even, one leg of the voltage
was up around 310 Vrms, and that I backed off on the capacitors so that
I was not over 110% of the name plate voltage.  I ended up with 1/3 the
amount of capacitors then Jim Hanrahans rule of thumbs.

  You just might want to check your voltages.

Good Luck

Vince

 
 
 

Fitch,3ph,et al

Post by DoN. Nicho » Fri, 20 Nov 1998 04:00:00




Quote:
>Wow! It really works!
>I have been using a 7.5hp idler motor with just capacitor start for
>several years and knew that the legs were not evenly balanced, but never
>had any problem running my equipment.
>The other day, I powered up a new hydraulic pump on a shop press, using
>a 1.5hp single phase motor and it stalled the motor. "Well", says I,
>"I've got a 5hp 3ph motor that I can use. No problem". After making the
>mounting mod's, I fired it up, using the rotary converter, and would you
>believe, it stalled the motor at just slightly higher pressure than the
>1.5hp?
>I dug out all of the 3ph stuff that has been floating around on the NG,
>including info by Fitch, Hanrahan, Carlson, plus a lot of miscellaneous

        [ ... details of balancing snipped ... ]

Quote:
>evenly matched on each side, I got readings of 7.5, 6.0, and 4.0
>respectively. Finally, it took 40mf more on one leg to get the final
>readings of: 6.0, 6.0, 5.5.
>Probably the most interesting thing was the major decrease in amperage
>from before the addition. Another was just how simple the entire thing
>was. It simply took recognising the necessity and then doing it.

        The one thing that I don't see mentioned in this article (though I'm
sure that you've actually done it) is a test of starting/running that
hydraulic pump on the modified system.  I presume that it is quite happy.

        Enjoy,
                DoN.

--
 NOTE:     spamblocking on against servers which harbor spammers.

 My Concertina web page:         | http://www.d-and-d.com/dnichols/DoN.html
        --- Black Holes are where God is dividing by zero ---

 
 
 

Fitch,3ph,et al

Post by Lee Marshal » Fri, 20 Nov 1998 04:00:00


Quote:

> Lee,

>   It's been a while since I got my converter up and running.  If I
> remember correctly, when I have the amps even, one leg of the voltage
> was up around 310 Vrms, and that I backed off on the capacitors so that
> I was not over 110% of the name plate voltage.  I ended up with 1/3 the
> amount of capacitors then Jim Hanrahans rule of thumbs.

>   You just might want to check your voltages.

Thanks for the suggestion. I've got to use the press tomorrow to run
some hot forging work and I will check it at that time.

Lee

 
 
 

Fitch,3ph,et al

Post by Lee Marshal » Fri, 20 Nov 1998 04:00:00


Quote:

>         The one thing that I don't see mentioned in this article (though I'm
> sure that you've actually done it) is a test of starting/running that
> hydraulic pump on the modified system.  I presume that it is quite happy.

>         Enjoy,
>                 DoN.

Most definitely! It just sits there and provides 25 tons of pressure as
needed. I am hot forging 1-1/8 steel bar into multiple curves by
bringing in secondary and tertiary cylinders by using a sequencing valve
after forming the primary curves with the main cylinder. I can now
perform the entire operation at a much lower temperature (which
generates much less scale with it's resultant pitting) and complete the
entire operation in about 4 seconds. These parts are mirror polished
after forming and the fewer pits to deal with the better.
As I said in the original post, I had recognised the problem a long time
ago, but simply never got "round-to-it" until forced to. :-)

Lee

 
 
 

Fitch,3ph,et al

Post by PeterH53 » Sat, 21 Nov 1998 04:00:00


I ended up with 1/3 the amount of capacitors then Jim Hanrahans rule of thumbs.

Hanrahan's single capacitor, self-starting converter requires about 30 to 35
microfarads per idler motor horsepower.

With 33 microfarads per idler horsepower, Hanrahan's converter produces a
manufactured phase which is within +/- 5 percent of nominal voltage, with the
unloaded value being 5 percent high and the fully-loaded value being 5 percent
low.

 
 
 

Fitch,3ph,et al

Post by Fitch R. Willia » Sun, 22 Nov 1998 04:00:00


Quote:

>Wow! It really works!
>I have been using a 7.5hp idler motor with just capacitor start for
>several years and knew that the legs were not evenly balanced, but never
>had any problem running my equipment.

<snipped fun post>

Quote:
>Thanks to all who have provided so much useful information on this and
>other subjects.

Good on ya!  I love it when opportunity and knowledge meet and blossom into a
good thing!

A suggestion:  Don't worry about current when tuning the output voltage.  Tune
the converter in two steps.  First, add capcitors to the thing till the two
generated voltages are around 110% of the line voltage.  If you wish, I will
send you an E-mail to explain which capacitor position affects what voltage.

Then, step two, add capacitance across the line untill the line current starts
to rise, then remove one, package it up nice and safely, and quit.  Forge stuff
and don't worry about it any more.  That is about as good as it gets.

Fitch
In So. Cal.

The FAQ (Frequently Asked Questions) for rec.crafts.metalworking
is at http://w3.uwyo.edu/~metal.  

The companion web page for rec.crafts.metalworking is the
Metal Web News at http://www.mindspring.com/~wgray1/      

The "Drop Box" for metalworking related pictures and binary files
is at http://www.metalworking.com/

 
 
 

Fitch,3ph,et al

Post by Fitch R. Willia » Sun, 22 Nov 1998 04:00:00


Quote:

>I fired it up, using the rotary converter, and would you
>believe, it stalled the motor at just slightly higher pressure than the
>1.5hp?

Yes, I would definately believe it.

Fitch
In So. Cal.

The FAQ (Frequently Asked Questions) for rec.crafts.metalworking
is at http://w3.uwyo.edu/~metal.  

The companion web page for rec.crafts.metalworking is the
Metal Web News at http://www.mindspring.com/~wgray1/      

The "Drop Box" for metalworking related pictures and binary files
is at http://www.metalworking.com/