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
And
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.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - Oil Bath Air Filters - by Chris Pratt. Some of us grew up thinking that an air filter was a paper thing that allowed air to pass while trapping dirt particles of a particles of a certain size. What a surprise to open up your first old tractor's air filter case and find a can that appears to be filled with the scrap metal swept from around a machine shop metal lathe. To top that off, you have a cup with oil in it ("why would you want to lubricate your carburetor?"). On closer examination (and some reading in a AC D-14 service manual), I found out that this is a pretty ingenious method of cleaning the air in the tractor's intake tract.
... [Read Article]
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.