×
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

PT shielded cable close to capacitor banks

PT shielded cable close to capacitor banks

PT shielded cable close to capacitor banks

(OP)
Does anybody know a type of PT cable that has a shield that will minimize transients due to magnetic coupling?  This is for a sub with cap banks.  We tried using a 4 conductor cable with a copper shield but it turns out that doesn't reduce magnetic coupling very well.

RE: PT shielded cable close to capacitor banks

What about using sheilded twisted pair? The shielding needs to be ferrous to shield for magnetic field, I believe.

RE: PT shielded cable close to capacitor banks

Scottf is right on, you need ferrous shielding for magnetic circuits.

Maybe you could run your wiring in steel conduit.

RE: PT shielded cable close to capacitor banks


It may be worth investigating if indeed magnetically-coupled capacitor currents are introducing errors in the PT cabling.  {As implied, non-ferrous shielding is primarily effective for electrostatic influence.}  

If for instance, the PTs are used for capacitor-unbalance protection, some initial or quiescent voltage may be present from accepted capacitor-manufacturing tolerances, and somewhat influence what would be considered an otherwise near-zero secondary quantity, like on the order of a 0.05 per-unit value.  The need for sensitivity in ground-overvoltage relaying makes accurate determination of ‘neutral-shift’ voltage quantities important, and otherwise not “buried in the mud.”  [Reference IEEE Std C37.99-2000.]
  

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