×
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

Speed fluctuation in VSD driven pump

Speed fluctuation in VSD driven pump

Speed fluctuation in VSD driven pump

(OP)
we have 3 LPG pumps(2+1) operated by separate VSD Motors(690 KW).
Nowadays we have the below problem.For ex.
Pump A & B runs at speed of 3000 rpm, then if small voltage dip occurs, then pump A speed goes to 100 rpm, then automatically comes to 3000 rpm. This cycle occurs within 50 secs. Pump B runs in same speed without any problem.

Why it is happening..? how to rectify the problem...?

VSD is by ANSALDO.

RE: Speed fluctuation in VSD driven pump

it depends what you mean by 'small' when it comes to the voltage dip. If the DC link drops below a certain threshold set within the drive, it will cut out.
If the drive has auto-restart then when the volts come back again, it will restart.
Check the settings between drive A and B. Maybe drive B has a function called 'kinetic buffering' or whatever they might call it. This will maintain control voltage longer than normal and ensure the drive does not cut out if sustaining a dip > the 'normal' 4-5 cycles.

 

RE: Speed fluctuation in VSD driven pump

Are these motors running independent pumps or are the two pumps piped in parallel?  If in parallel, are the VFD's running independently against independent setpoints or are the two VFD's linked together in some way?  If linked, please describe how.

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