×
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

Polycarbonate Stress Shields

Polycarbonate Stress Shields

Polycarbonate Stress Shields

(OP)
Hi,

We have had an insulation breakdown in an 11kV VCB.  We have sent this away for investigation and the culprit was a stress shield mounted on the end of the vacuum bottles.  The clear shields had black traces on them.  We have been informed that Polycarbonate will sooner or later give up it's carbon when surrounded by an electrical field.  Has anyone else experienced this or have any further information?

Many Thanks

RE: Polycarbonate Stress Shields

Hi
I have seen many cases like this.
In the circuit breaker you have four main active parts the mechanism, the vacuum bottles, the (shields & insulators) and the (wiring & control).
I guess you have no trouble with the mechanism and the wiring & control.
If you have tested the vacuum bottles and they are OK, you have only one part remaining.. the shields.   
The decision for keeping or replacing the shields depends on the cracks, if there are cracks in the shields you have to change them because any cleaning or repairing will be useless, but if the carbon is just covering the shields and not effected their material, you can just clean them and use the circuit breaker again without any troubles. Most of the times the shields are not destroyed  in one breakdown.

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