×
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

Motor starting frequency

Motor starting frequency

Motor starting frequency

(OP)
What is the meaning of the following in relation to pump starting:
 
Motors shall withstand at least:
 3 consecutive starts, at 80% Un, with load inertia according to IEC60034-12.

RE: Motor starting frequency

This is partly a guess...

1 The motors should be able to withstand 3 consecutive starts.  This requirement would be for larger motors.  Many large motors are limited to 2 starts per hour.  This is especially true if they have a high inertia load which would cause the motor to have an extended start time.

2. The 80% Un...I assume this refers to the minimum starting voltage of 80% of nameplate.  That's a common minimum allowable starting voltage.

3. I'm not familiar with IEC standards.

RE: Motor starting frequency

IEC60034-12 specifies starting requirements for motors depending on their type(N,H,NY or HY). If you can specify type of your motor, which depends on number of poles, power and starting method (DOL or star-delta), I'll be more helpful.  

RE: Motor starting frequency

(OP)
Thanks for the response. The specification is a design requirement relating  to pumps which will be rated each at between 500 kW and 1 MW.  ( I think it is premature to be specifying limits on motor start frequencies when the requirements for the pumps and motors have not yet been determined.)

I am asking mainly from interest - I have not seen the requirement "80% Un, with load inertia according to IEC60034-12" -  before and searching through IEC60034 -12 did not enlighten me at all.

 

RE: Motor starting frequency

Ok. For each motor type (think your will be N or NY if star-delta capable) that standard defines minimum torques, maximum locked rotor apparent power and number of starts (two starts from cold and one from hot are specified in general), and external inertia under which requirements shall be fulfilled. At least that's my understanding of it. When the time comes for more detailed data/questions, hope I'll be able to help.

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