Yesterday's Tractor Co. Shop Now
   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver
Classified Ads
Photo Ads
Tractor Parts

Discussion Forums
Project Journals
Tractor Town
Your Stories
Show & Pull Guide
Events Calendar
Hauling Schedule

Tractor Photos
Implement Photos
Vintage Photos
Help Identify
Parts & Pieces
Stuck & Troubled
Vintage Ads
Community Album
Photo Ad Archives

Research & Info
Tractor Registry
Tip of the Day
Safety Cartoons
Tractor Values
Serial Numbers
Tune-Up Guide
Paint Codes
List Prices
Production Nbrs
Tune-Up Specs
Torque Values
3-Point Specs

Tractor Games
Just For Kids
Virtual Show
Museum Guide
Memorial Page
Feedback Form

Yesterday's Tractors Facebook Page

Related Sites
Tractor Shed
Ford 8N/9N Club
Today's Tractors
Garden Tractors
Classic Trucks
Kountry Life
Tool Talk Discussion Forum

Re: Electric motor: power vs. rpm

[Show Entire Topic]  

Welcome Guest, Log in or Register
Author  [Modern View]
missouri massey man

12-24-2013 13:52:59

Report to Moderator

Unless you are rasonably well versed with electricity, I wouldn't recommend you or anyone else to try to build you own rotary phase converter....that being said,

The reason many home made converters seem to have less than a stellar performance is that they usually apply incoming power to the rotary converter with the third leg through a run capacitor (or capacitors in parallel) without first using a "pony" motor and a time delay relay to get the 3 phase motor "up to speed" first.
Sure, it will start on single phase by paralleling one of the legs through the capacitor to the third winding, but it will never attain full speed, consequently not optimum output either. However.... using a pony motor with the same rpm rating of the 3 phase motor you are using and connect them together with a lovejoy coupling or even same size sheaves and a belt you will first get the driven motor to full speed then the time delay relay will drop power off of the pony and simultaneously apply 220v single phase with the third leg going through the capacitor AFTER full rpm is achieved. It still will not supply the rated power, but it will perform remarkably better.
Typically one 20 mfd oil filled run capacitor will suffice on most small 1, 2, 3 and even a 5 hp three phase motor. It's not going to be perfect, and it is considered a pretty dirty three phase power, it will work for a home work shop. With an oscilloscope and a pile of additional capacitors, in theory, you should be able to keep adding capacitance in parallel until you get very near to a 120 degree phase shift. A three phase motor has three identical windings and with correct three phase power applied, has 120 degrees phase shift between the three windings. That is the reason they are referred to as a motor with "high starting torque".

Without the capacitor, you will "single phase" the motor and it will literally smoke in minutes....all the capacitor is doing is creating a little offset in the third leg (ergo: phase shift) to allow rotation to initiate. Not being a perfect 120 degree phase shift is what causes it to be underpowered. Nature of the beast.

That all being said, this description is totally incomplete and not intended to suggest that you should try it at all !!! But it DOES work for me in the way it is described. As a matter of fact you should be able to easily run a total horsepower higher than that of the motor you are using for the rotary converter.
Not for the faint of heart, and NOT RECOMMENDED for a rookie with little or no electrical background.....BE SAFE !!!!! ...and enter John T's normal disclaimer here: "____________________"

[Log in to Reply]   [No Email]
George Marsh

12-24-2013 19:47:05

Report to Moderator
 Re: Electric motor: power vs. rpm in reply to missouri massey man, 12-24-2013 13:52:59  
From a previous post, Brad said the motor is 560vac 3 phase, 600 rpm. All 3 phase converters my dad made were 220v. I don't know where he is going to get 560 vac 3 phase in this country.

[Log in to Reply]  [No Email]
T in NE

12-25-2013 15:13:33

Report to Moderator
 Re: Electric motor: power vs. rpm in reply to George Marsh, 12-24-2013 19:47:05  
The volt meters in all the pivot control boxes I have looked in showed around 550 volts.

[Log in to Reply]  [No Email]
[Show Entire Topic]     [Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:

Fast Shipping!  Most of our stocked parts ship within 24 hours (M-Th). Expedited shipping available, just call! Most prices for parts and manuals are below our competitors. Compare our super low shipping rates! We have the parts you need to repair your tractor. We are a company you can trust and have generous return policies. Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ About Us ]

Home  |  Forums

Copyright © 1997-2018 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters