×
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

Rotational inertia of 75 hp motor

Rotational inertia of 75 hp motor

Rotational inertia of 75 hp motor

(OP)
I'm looking for a quick and dirty number for the rotational inertia of a 75 hp, 460 V, 3 phase TEFC motor.  Nothing super accurate, just a ballpark.  

Thanks in advance for the help.  :)

RE: Rotational inertia of 75 hp motor

From ABB catalog:
NEMA 460 V [60 Hz] 8 poles 75 hp 59 lb-ft^2: 6 poles 75 hp 39 lb-ft^2; 4 poles 100 hp 23 lb-ft^2 ; 2 poles 100 hp 14.5 lb-ft^2
 

RE: Rotational inertia of 75 hp motor

(OP)
Thanks.  Is that catalog online anywhere?  I couldn't find it.

RE: Rotational inertia of 75 hp motor

Another quick easy estimate: NEMA MG-1 has a formula for estimating motor rotor inertia for the purposes of dynamic braking calculations.
WK2 = 0.02*2^(poles/2)*hp^(1.35-0.05*poles/2)
where
HP is output power rating in HP.  
WK^2 in ft^2-pounds

They don't distinguish ODP vs TEFC, so that tells you it's not tremendously exact.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

RE: Rotational inertia of 75 hp motor

(OP)
That's perfect!  Thanks electricpete - just what I needed. <star>

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