×
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

minimum air clearance in transmission line

minimum air clearance in transmission line

minimum air clearance in transmission line

(OP)
I have this double circuit 220kV line and the formula used for designing minimum air clearance between conductor and earthed part is a = 6.5 inch per 10kV rms; Is this an european or US standard? Thanks in advance

RE: minimum air clearance in transmission line

Samundra24,
the clearance depends on the required impulse withstand (switching / lightening) and not on the nominal voltage, which generally dictates the creepage distsnce.
The correlation between standard rated voltages, rated impulse withstand voltages and minimum air clearances are reported in IEC 60071.
For a 220 kV system (Um=245 kV), the highest standard BIL is 1050 kV, leading to a standard conductor-structure clearance distance of 1.9 m.

Si duri puer ingeni videtur,
preconem facias vel architectum.

RE: minimum air clearance in transmission line

That doesn't sound like anything directly out of the USA NESC. Table 235-6 requires 11 inches + 0.2 inches per kV over 50 kV for the distance from conductors to the supporting structure.

Clearances from other objects such as buildings are typically listed as a base value plus 0.4 inches per kV over 22 kV phase to ground (6.92in/10 kV Phase to phase).

RE: minimum air clearance in transmission line

(OP)
Thanks a lot guys.

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