×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Increase the Output Frequency of ABB-ACS550 Drive
2

Increase the Output Frequency of ABB-ACS550 Drive

Increase the Output Frequency of ABB-ACS550 Drive

(OP)
Hello Everyone!

Recently we purchased an ABB-ACS550 drive and connected it to a 5.5KW motor.When we tried to increase the output frequency above 150HZ the motor speed increases correspondingly but above 105Hz , the motor slows down and stops.
When the output frequency is then decreased the motor suddenly speeds up for a brief period and stops again.
Could anyone kindly explain as to why this happens and provide us with a solution?

Thanks so much in advance!

RE: Increase the Output Frequency of ABB-ACS550 Drive

Protecting you from your deaths? You must realize you cannot run a motor at any speed you feel like? Asking it to go considerably faster than twice its rated speed is asking for it to grenade on you.


Safety aside a motor is designed to a specific Volts/Hertz ratio of magnetic excitation. As you overspeed the motor supplying it higher and higher Hertz without doing anything about the Volts you are driving the motor farther and farther from its designed region of operation until it becomes unstable and loses sync with the magnetic field its chasing which causes it to simply stop.

You also are reducing the motor's torque from its rated torque for every Hertz you go above the frequency listed on its plate.

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

RE: Increase the Output Frequency of ABB-ACS550 Drive

(OP)
Thanks so much for your valuable feedback Sir! We actually thought this occurrence was due to the type of application macro we selected in the ABB -ACS550 drive, but we were wrong. We have now taken safety limits into account and set the maximum frequency of the drive back to 50 Hz and are operating the motor below this range peace

RE: Increase the Output Frequency of ABB-ACS550 Drive

Good to hear. Glad you came by for some advice!

Carry on.

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

RE: Increase the Output Frequency of ABB-ACS550 Drive

A VFD allows an AC induction motor to change speed and manitain rated torque by maintaining the ratio of voltage and frequency that it was designed for, aka the "V/Hz ratio". When you get to full rated frequency, in your case 50Hz, the VFD is at full voltage, probably 400V, so a V/Hz ratio of 8:1. But the VFD cannot create voltage that is above what you feed it, so 400V is the maximum. When you continue to increase the Hz without increasing the volts, you are operating the motor at a constant POWER, not a constant torque because you are weakening the fields in the motor. So as that V/Hz ratio changes, the torque changes at the SQUARE of the ratio change. Assuming then that you are 400V 150Hz, your ratio went from 8:1 down to 2.67:1, so 33.3%, meaning your shaft torque became just 33.3%2 or 11% of the motor rated torque. At that point you enter the region of the motor not having enough torque to move it's own rotor mass, let alone a load, so it slows down.

VFDs have the ability to run at higher frequencies because there are MOTORS designed to run at higher frequencies. These are often called "Spindle Motors" for high speed machine tools and you will see on the nameplate that it is designed for 400V 400Hz or something like that. THAT is when you need that feature in a VFD.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

RE: Increase the Output Frequency of ABB-ACS550 Drive

(OP)
Thanks Sir for taking the time to explain so clearly, It all makes sense now!
The place where we went wrong was to assume that the motor would run at any RPM as long as the VFD allows for it (clearly that isn't the case). We understand now why the motor was behaving in this way and have taken precautions to run the motor at it's base frequency smile

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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