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]
Indiana Ken

12-24-2013 17:00:27

Report to Moderator

Quoting Removed, click Modern View to see

I am not a electrical expert so others will need to check my assumptions concerning motor operation with a VFD. However, the relationship between HP and Torque is as follows:

1) HP = (T x RPM) / 5252
2) T = (HP x 5252) / RPM

From 2) we see that 3 HP at 600 RPM requires 26.26 ft-lbs of torque ((3 x 5252) / 600 = 26.26).

From 1) we can can plug in the 26.26 ft-lbs of torque to determine what the motor HP would need to be at rated RPM. We can also see it would be better to start with a 1750 RPM motor rather than a 3600 RPM motor. We see that a 8.75 HP, 1750 RPM motor would be required to produce 26.26 ft-lbs of torque at 600 RPM ((26.26 x 1750) / 5252) = 8.75 HP).

Note the above assumes that a 3 phase motor will make full rated torque a 600 RPM when operated with a VFD. Since the motor is producing 3 HP it should draw similar wattage to that of a 3 HP motor running at rated speed. I say similar since there will be some loss in the VFD etc. The motor cannot produce its rated power (HP) at 600 RPM since it is not running at rated RPM, see equation 1).

Those who are more knowledgeable in electric motor operation please add any corrections as required.

[Log in to Reply]   [No Email]
Brad Buchanan

12-24-2013 19:32:48

Report to Moderator
 Re: Electric motor: power vs. rpm in reply to Indiana Ken, 12-24-2013 17:00:27  
I was thinking that I might have to double the HP but you figures may cause me to update that.


[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