×
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

supply voltage effects and motor design

supply voltage effects and motor design

supply voltage effects and motor design

(OP)
Hi all,

It is common motor knowledge that motor torque declines by the square of the change in supply voltage.
However, there are motors designed for 230 or 460 volts, and torque is the same at all rpm for 230 or 460Volts, with only a change in drawn motor current.
so in this case supply voltage can drop by half, but torque does not change at all. Is this a function of design?
can someone explain?
Thank you.

RE: supply voltage effects and motor design

To make the story short, keep constant the torque by keeping the volts/turn/hertz constant.
For your example; 230/460 volts motors; a change of connection is required. Series connection at 460 Volts, parallel connection at 230 Volts.
If all coils per phase are series connected you have double of the turns connected to 460 volts, parallel connection has half of those turns connected to 230 volts but with two paths for current which takes care of the increased current at 230 volts to handle the same power. For this case the frequency is constant so the motor spins at the same speed in both connections.
When VFD’s are used; the frequency is changed too but the voltage must drop proportional to frequency, so the volts/turn/hertz ratio is kept constant..

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