Shop Floor Talk  

Go Back   Shop Floor Talk > Welding and Metalworking Forums > Shop & Safety

SFT Search:   
Reply
 
Thread Tools Display Modes
  #1  
Old 06-23-2005, 01:38 PM
7018's Avatar
7018 7018 is offline
Elite Member
 
Join Date: Jun 2004
Location: SnakeBite Al.
Posts: 2,992
Send a message via Yahoo to 7018
Default Phase Converter Question????

I went out hunting a 3 phase motor this morning,When every where I could think of going out about 4 hrs hunting.Well I kinda give up for today so I was heading home I callled my junk man buddy to see if he was home,He was so I told him I'd stop by for a few.When I drove up I saw somenew in the yard...I went to look at it.On it was a 7/12 horse 3 phase motor,But the bearings are froze at least I hope so..Its a 1750 rpm motor.Now heres the question If I can't fix this one there is also a 10 hp motor on the machine that turns free but its a 3700 rpm motor and I know that they say use around 1800 rpms can I use the 3700 rpm motor???????These motors are free!!!
__________________
This post brought to you by the bringer of chaos, doom, change, and technology... Asker of questions, challenger of assumptions, solver of problems and share-er of ideas
Reply With Quote
  #2  
Old 06-23-2005, 02:12 PM
cutter's Avatar
cutter cutter is offline
Curmudgeon
 
Join Date: Jun 2004
Location: Lubbock,Texas
Posts: 32,885
Default

Quote:
Originally Posted by 7018
can I use the 3700 rpm motor???????These motors are free!!!
Well, er .. ah OOPS! Man, you got me. I never considered that question before. But I 'spect Franz or Stovepoker have.
My idler motor is 1750 rpm & my compressor motor is 1725. BUT my drill press motor is 2-speed, 1800 & 900. The low speed works fine which would lead me to think that the rpm relationship isn't a factor but that is based on too little data to be reassuring.

(ten minutes later)
Paul, I did a little digging through the reference materials I used as a guideline for building mine & found this statement:
"The speed rating is not important; from 1100 to 3600 RPM are all fine. The higher speed might produce slightly better phase angles, but the lower speed is generally easier to start."

That came from this website & you might like to file it away for future reference:
BUILDING A PHASE CONVERTER
By Jim Hanrahan
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html

And since the motor is free, take it! It'll probably work out ok but I'd still like to hear what the other guys say when they weigh in.
__________________
cutter
Housekeeping Staff: the Gatekeeper
Director of Policy, Syntax and Grammar (by appointment)

"Dr. Chandran, will I dream?"

Just Keep Walking

"Passionate hatred can give meaning and purpose to an empty life. Thus people haunted by the purposelessness of their lives try to find a new content not only by dedicating themselves to a holy cause but also by nursing a fanatical grievance. A mass movement offers them unlimited opportunities for both."
Eric Hoffer The True Believer 1951
Reply With Quote
  #3  
Old 06-23-2005, 02:16 PM
7018's Avatar
7018 7018 is offline
Elite Member
 
Join Date: Jun 2004
Location: SnakeBite Al.
Posts: 2,992
Send a message via Yahoo to 7018
Default

Thanks for the fast answer cutter!!I didn't want to leave the motor setting over there to long it mite go somewhere else..I'll call the guy and tell him I want it.And I'll also check the web site you posted.Thanks again....
__________________
This post brought to you by the bringer of chaos, doom, change, and technology... Asker of questions, challenger of assumptions, solver of problems and share-er of ideas

Last edited by 7018; 07-18-2005 at 01:25 PM.
Reply With Quote
  #4  
Old 06-23-2005, 02:24 PM
cutter's Avatar
cutter cutter is offline
Curmudgeon
 
Join Date: Jun 2004
Location: Lubbock,Texas
Posts: 32,885
Default

Cool & you're welcome. I hope it works out for you.
I suspect you'll have to load up on starting capacitors a little more to bring it up to speed so you might check to see what he has on hand (if any) in the 100 - 200 mfd range. You're going to need a bank of 600 - 700 mfd, minimum. And an extra contactor for the starting circuit, and ......

And believe it or not, I have to go work a little while now.
(But its a garbage disposal, single phase.)
__________________
cutter
Housekeeping Staff: the Gatekeeper
Director of Policy, Syntax and Grammar (by appointment)

"Dr. Chandran, will I dream?"

Just Keep Walking

"Passionate hatred can give meaning and purpose to an empty life. Thus people haunted by the purposelessness of their lives try to find a new content not only by dedicating themselves to a holy cause but also by nursing a fanatical grievance. A mass movement offers them unlimited opportunities for both."
Eric Hoffer The True Believer 1951
Reply With Quote
  #5  
Old 06-23-2005, 02:26 PM
Pile Buck's Avatar
Pile Buck Pile Buck is offline
North West Redneck
 
Join Date: Dec 2004
Location: West of Seattle
Posts: 2,441
Default

Hi 7018, the idler motor for my phase converter is a Westing House 10-HP 3480 RPM. I have it hooked up to a Phase-A-Matic converter, works great. Just way to noisy for me!
Attached Thumbnails
Click image for larger version

Name:	Idler.jpg
Views:	514
Size:	29.9 KB
ID:	4615  
Reply With Quote
  #6  
Old 06-23-2005, 02:27 PM
Pile Buck's Avatar
Pile Buck Pile Buck is offline
North West Redneck
 
Join Date: Dec 2004
Location: West of Seattle
Posts: 2,441
Default

Here are all the switches
Attached Thumbnails
Click image for larger version

Name:	Switches.jpg
Views:	540
Size:	38.4 KB
ID:	4616  
Reply With Quote
  #7  
Old 06-23-2005, 02:40 PM
7018's Avatar
7018 7018 is offline
Elite Member
 
Join Date: Jun 2004
Location: SnakeBite Al.
Posts: 2,992
Send a message via Yahoo to 7018
Default

I've got 4 start capacitors and 3 run caps 1 phase contactor and 1 power contractor I've got to pickup a discharge resistor and a box But I think I've got what I need.I also have a phase converter but its only for a 3/4 horse...I hope thats all I need,there is some contactors on the machine but I don't think I'll need anymore the Lathe has its own.It also has a transformer to pickup the 110 control voltage....So it should work then!!!!
__________________
This post brought to you by the bringer of chaos, doom, change, and technology... Asker of questions, challenger of assumptions, solver of problems and share-er of ideas
Reply With Quote
  #8  
Old 06-23-2005, 03:47 PM
Franz Franz is offline
Banned
 
Join Date: Jun 2004
Posts: 5,731
Default

Paul, ideally you go with the slowest 3 phase motor you can find for the idler, 900 or 1200 rpm, even 1800 if you can't find slower.
The slower the motor, the more poles it has connected in the stator, and the greater the efficiency.
Now, ideally don't really come into play if you can't find a slow motor, and 3600 rpm will work. Were I in your situation, I'd build on the 3600 motor, and change it out when I found a slower motor.
One of the best sources of information on phase converters is on Practicle Machinist, they have a whole section dedicated to converters.
Reply With Quote
  #9  
Old 06-23-2005, 04:40 PM
7018's Avatar
7018 7018 is offline
Elite Member
 
Join Date: Jun 2004
Location: SnakeBite Al.
Posts: 2,992
Send a message via Yahoo to 7018
Default

Quote:
Originally Posted by Franz
Paul, ideally you go with the slowest 3 phase motor you can find for the idler, 900 or 1200 rpm, even 1800 if you can't find slower.
The slower the motor, the more poles it has connected in the stator, and the greater the efficiency.
Now, ideally don't really come into play if you can't find a slow motor, and 3600 rpm will work. Were I in your situation, I'd build on the 3600 motor, and change it out when I found a slower motor.
One of the best sources of information on phase converters is on Practicle Machinist, they have a whole section dedicated to converters.
Well now it seem like I'm going to have to use the 3600 rpm one! The wire accress cover was gone on the 1800 rpm moter so now I know why it wouldn't turn its full of water!!!!!The only other motor I found to day was on a bridge port mill for 1500.00 and I'm going to try and get the money up for that.......
__________________
This post brought to you by the bringer of chaos, doom, change, and technology... Asker of questions, challenger of assumptions, solver of problems and share-er of ideas
Reply With Quote
  #10  
Old 06-23-2005, 07:51 PM
7018's Avatar
7018 7018 is offline
Elite Member
 
Join Date: Jun 2004
Location: SnakeBite Al.
Posts: 2,992
Send a message via Yahoo to 7018
Default

well I went and got the other motor it is a 3500 rpm it seems to be ok,anyway I hope so!!!
__________________
This post brought to you by the bringer of chaos, doom, change, and technology... Asker of questions, challenger of assumptions, solver of problems and share-er of ideas
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Web Search:

All times are GMT -5. The time now is 11:12 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.