×
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

Undervoltage definition
2

Undervoltage definition

Undervoltage definition

(OP)
Could you please advise me about the meaning of the protection function 27i. ( I Know that the ANSI Code for undervoltage protection is [27] but i did never hear about 27i. Also what is 27R ( somebody said:residual undervoltage). Does this function exist? if so whatis its application?
Thanks in advance.

RE: Undervoltage definition

Residual Voltage or Unbalanced Voltage protection is normally included in an ungrounded system where under single to ground fault leads to 1.732X VL increase to healthy lines. S-L-G fault leads unbalanced condition in a balanced system. So its better to include Unbalanced protection as it is faster & relates insulation co-ordination.

Generalised setting for 27R may be assigned as >20% with 5Sec & >50% instantaneous.

This also reduces the arcing ground under S-L-G fault.

(A Singh)
IOCL, India

RE: Undervoltage definition

(OP)
dear 27 i is instataneous under voltage and 27 r is residual under voltage.

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