×
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

132/11kV transformer neutral cable

132/11kV transformer neutral cable

132/11kV transformer neutral cable

(OP)
Dear all,

Why the neutral cable gland shall be insulated from the cable box on the 11kV side of 132/11kV transformer? Also, why the 11kV neutral cable sheath shall be insulated? Is it related to the neutral current transfomer.

Thank you!!

RE: 132/11kV transformer neutral cable

eejacky,

Is the neutral intended to be solid earthed, or impedance earthed? If the neutral were not isolated from the cable box, it would not be possible to use impedance earthing, as this would cause the transformer cable box and everything attached to it to rise above ground potential during a fault or imbalance.

Assuming the neutral cable is a normal XLPE/SWA/PVC type, the sheath keeps water off the XLPE insulation. XLPE is hygroscopic, meaning it absorbs water over time. When it absorbs enough water, the insulation fails. The sheath also stops the SWA corroding. It isn't really 'insulation', although it has obviously got some degree of insulating properties.


RE: 132/11kV transformer neutral cable

I assume that the 11kV side ( N that is) is earthed, either solidly or via  a NER.
I also assume that by cable "sheath", you mean the cable armour.

If my assumption is correct then, conterary to what you say, you would be wise to ensure that the cable armour is bonded to the cable box gland plate via the cable gland, ie making sure that the armour is indeed earthed and not insulated.

The current transf ( which I presume is fitted in the N term box) has nothing to do with the treatment of the cable armour earthing.

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