×
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

Induction Motoro Rotor Copper losses

Induction Motoro Rotor Copper losses

Induction Motoro Rotor Copper losses

(OP)
The question is:

The rotor of a 3 phase 60hz 8-pole induction motor takes 220w @ 3hz. Find the rotor speed and the rotor copper losses.

Here is what I have done so far:
I have found the rotor speed by using the equation slipspeed = fr(120)/P = 3hz(120)/8 = 45 rpm then finding nsync by 120(60)/8 = 900rpm so rotor speed = 900-45 = 855rpm. Slip can also be found to be 5% from this. I am stuck at trying to find the rotor copper losses though. I thought that it was just the 220w but that seems too easy. I would appreciate any help with this problem. Thank you.

RE: Induction Motoro Rotor Copper losses

(OP)
Never mind I figured it out. It is slip*(input power to rotor) so .05*220w = 11w

RE: Induction Motoro Rotor Copper losses

Pretty darned close.  

If you want to get sharpen you pencil to get a hair closer:
1 - subtract out your estimate of stator losses and other non-rotor losses from input power first (that should leave you with airgap power).
2 - multiply by s/(1-s)   instead of  s

=====================================
(2B)+(2B)'  ?

RE: Induction Motoro Rotor Copper losses

Naughty naughty, no homework help here... read the rules.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln  
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies  

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