×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Stack dimension relationship to power

Stack dimension relationship to power

Stack dimension relationship to power

(OP)
I've heard that for AC motors, P=(d^2)*L, where P is power, d is diameter of laminate stack and L is the stack length.  True?  If so, d is ID of stator, right?  And P is watts?

RE: Stack dimension relationship to power

For a material of given permeability and a design of given air gap and constant supply frequency then yes I guess that Power = constant x d^2 x l  (in other words the magnetic volume). But the formula is largely useless because the 'constant' depends on almost everything associated with the motor including winding type, speed of rotor, air resistance, magnetic circuit shape, bearing losses, lamination design and so on.

RE: Stack dimension relationship to power

(OP)
Thanks Aranrhod.  Is there any way to get an understanding of what variables affect the "constant" you mention?  I just need a convenient way to determine the power (or specifically torque) of various motors by varying the diameter or length.For instance, if I need 0.76 lb ft of torque at 3450, and a motor with say 4.25" stack length and 0.9" diameter can produce only 0.11 lb ft, what diameter/length ratios would I need to get there?

RE: Stack dimension relationship to power

Suggestion: The relationships that are sought are more on an empirical side. For example:
Output HP = Co x N x L x D**2
where
HP is horsepower
Co is factor
N is r.p.m.
D is diameter or aigap or rotor in centimeters or inches
L is length in centimeters or inches
Also,

Co=Bav x q x eta x cos(fi)/(4 x 10**11)

Bav = Total pole flux FI / total area of the gap per pole
as if the pole faces were of smooth iron
q is the specific ampere-conductors per cm of periphery
eta is efficiency
cos(fi) is power factor


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources