×
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

Issues with UPS power for motor starter

Issues with UPS power for motor starter

Issues with UPS power for motor starter

(OP)
One of my collegues has proposed to use designated UPS to feed all low voltage motor control relays, including the control power for the coils. One of major issues  is, UPS will hold all the coils even though the main power is lost. Upon the recovery of the main power supply, all the motors will be started simutaneously and will cause excessive voltage dip in the system. This would cause overheating of motors. Any otehr potential issues other than what I described above. Appreciate it for any comments.  

RE: Issues with UPS power for motor starter

Hi Hamid;
I would not use a UPS for controls unless special circumstances demanded it. One possible use may be to power an AVR if a generator was being used as a poor man's VFD.
If I found that I had to supply a control scheme from a ups, I would add a power failure relay and a PLC. In the event of a power failure the PLC would drop out the motor starters and restart them in an orderly fashion.
If you are anywhere near Edmonton I will be coming in through Camrose on Monday.
Happy to buy you a coffee if we can connect.
Yours
Bill

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

RE: Issues with UPS power for motor starter

Alternatives:

Use a sequential restart scheme. These used to be built using pneumatic timing relays, today would likely use a PLC

Use a DC control voltage and feed the motor starters from a tripping & control battery.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

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