×
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

ac motor control

ac motor control

ac motor control

(OP)
does anybody know if a single phase 115 vac motor, running at around 1700 rpm  come to a dead stop if the power is switched off? by the way, the motor is driving a conveyor and the speed of the conveyor is being reduced first by a 30:1 gear box.

The idea is to start/stop the conveyor using a programmable relay.

Thanks.

RE: ac motor control

With a 30:1 gearbox the reflected inertia from the gearbox output shaft to the motor shaft will be very low.  The load will most likely "wind down" very quickly if there is and amount of mechanical damping in the system on the load side.  The motor stops producing torque as soon as the power is removed from the terminals.  The design of the gearbox will have a large impact on how easy or difficult it is to drive the output shaft.  

RE: ac motor control

"... running at around 1700 rpm  come to a dead stop ..."

You left out an operative in between "rpm" and "come". Should? would? could? will? must? might? can? wants to? better not or I'll tell your father when he gets home?

In general though, the coast-to-stop time is dependant upon the load, not the motor. High inertia combined with low friction would mean a long coast time, low inertia with high friction would mean a very short coast time. Any combination variables of those two load components will result in an infinately variable outcome. In other words, no way to tell with the information you provided.

That said, conveyors are typically low inertia high friction, and combined with a 30:1 gear reduction, it is likely that it will stop quickly. But is the conveyor load going down hill? Is there a flywheel or dancer on it that has enough mass to keep it going? Is the gear reduction going the other way (I can't imagine a conveyor pulley running at 51,000rpm, but hey, who knows)?

"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more."   
Nikola Tesla

RE: ac motor control

"comes" perhaps?

English is not so easy for us foreigners...

Gunnar Englund
www.gke.org

RE: ac motor control

Oops, duh. English is difficult even for some of the rest of us who have been speaking it all out lives!

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