×
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

Can I make this motor variable speed?

Can I make this motor variable speed?

Can I make this motor variable speed?

(OP)
Attached are some pictures of the motor I've got. Its powered by 110v AC. Right now it just has an on/off switch. Is there a way to make this motor variable speed?



RE: Can I make this motor variable speed?

Single-phase motors with capacitors in the start or run circuits are pretty much single-speed machines.

You might be able get a 3-phase motor of equal output in the same or a smaller frame size, and then use a little VFD to to control it. The VFD part is the easy bit in that case - the mechanical arrangement might be a little more challenging. It's hard to tell what the load is, and how the motor is coupled to it.

RE: Can I make this motor variable speed?

Yes, you can!

Remove the capacitor and switch. Get yourself a VFD and "teach" it. If the motor isn't designed for permanent helper winding operation, then keep the centrifugal switch. And make sure you get an el cheapo VFD that doesn't mind if the load is unbalanced.

A VFD produces a better phase displacement than a capacitor ever can.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Can I make this motor variable speed?

(OP)
It sounds like it might be cheaper to buy a variable speed motor with some kind of controller. anyone have any recommendations on a motor that will produce the same amount of torque as this one and allow me to vary the speed?

RE: Can I make this motor variable speed?

Cheaper, simpler, safer. You got it.
Special solutions can be necessary if the motor has special dimensions that cannot be had with a standard motor.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Can I make this motor variable speed?

Yes, you're probably correct.

You want good advice tell us A LOT more so we can advise you from an informed position.

What power do you have?

What is this motor doing?

What is its duty cycle?

What is the environment; dusty, wet, outdoors?

A lot of electronic controls around?

Why do you want the speed to change?

Could a "speed controller" be mounted near this motor or how far away?

Does your facility seem to have any power problems?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Can I make this motor variable speed?

Automation direct will sell you a 0.5 HP rated, inverter rated motor in a 56C frame with a rigid base.
This should be a drop in fit.
Avoid a 56T motor, the shaft will be a different diameter.
You will probably have to supply 230 Volts, either directly or with a transformer.
You will probably get a service factor of 1.15 instead of 1.25.
If you are going to run the motor at maximum rated torque continuously this may be a problem.
In the overwhelming percentage of applications the 1.15 service factor should be adequate.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Can I make this motor variable speed?

I think you can.

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