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


Medium Voltage drop calculation

Medium Voltage drop calculation

Medium Voltage drop calculation

Looking to calculate voltage drop on a 12kV ciruit that is a few miles long. Is the voltage drop formula for medium voltage the same as low voltage. Anyone know of a link to an online voltage drop calculator?


RE: Medium Voltage drop calculation

The Ohm's law, V=IZ is the formula, which remains the same. You need to get the right impedance (X and R) data.  Use per phase values.

Just be careful as to what formula you use, as some 'customized' formula would ignore reactance for smaller size wires at low voltages and you cannot ignore that at higher voltages.

You may want to visit some MV cable manufacturer's website such as okonite.com to get some assistance and data.

As for the link, your web search would be as efficient as mine.

Rafiq Bulsara

RE: Medium Voltage drop calculation

for balanced loads, the voltage drop formula is the same:

VD = I·(R·cosø + X·sinø) where power factor = cosø

If your phases are not balanced, things get more complicated.  You can account for the imbalance by using a sequence phase impedance model as described in "Distribution Feeder Line Models" by W.H. Kersting of New Mexico State University.  This model correctly accounts for the effect of unbalanced loading and mutual coupling for fully transposed lines using standard equations for sequence impedances.

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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close