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


Motor turn down - what does it mean?

Motor turn down - what does it mean?

Motor turn down - what does it mean?

In a new position at work, and guys around me are talking about motor "turn down".

Would someone please give me a description of what "turn down" means.



RE: Motor turn down - what does it mean?

Sure someone else can explain this a bit better than I can but as far as I'm aware, turndown ratio is simply the ratio of the rated speed to the minimum speed at which the motor can handle the rated load.
Therefore a higher turndown ratio implies slower speeds are possible without causing damage.  i.e. the speed can be "turned-down" more.

RE: Motor turn down - what does it mean?

I've heard the term in relation to motors with variable speed capabilities, i.e., variable speed drives, and "turn down" is the minimum speed that the motor will be useful, such as able to spin up the load equipment.

Our motors have a range of 50-105% RPM.  At 50%, the centrifugal compressors are  spinning but at normal operating pressures they're performing very little compressing.

old field guy

RE: Motor turn down - what does it mean?

I have always known the phrase "turn down" to express the ratio of maximum over minimum in regards to a variable quantity.
Example; a gas burner will operate over a range of 250,000 BTU/Hr. to 10,000,000 BTU/Hr. The turn down ratio is 10,000,000/250,000 = 40 or 40:1
Does this explanation fit your context?

"Why not the best?"
Jimmy Carter

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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close