×
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

Why Flashover for + polarity is less than - polarity?

Why Flashover for + polarity is less than - polarity?

Why Flashover for + polarity is less than - polarity?

(OP)
We know that if a positive polarity surge is applied to rod in air with the plane grounded, the flashover voltage will be substantially lower than if a negative polarity surge is applied to the rod with the plane grounded.

However, it is not obvious why.

Your comments or provide a reference will be appreciated

Thanks
 

RE: Why Flashover for + polarity is less than - polarity?

Imagine the rod is positive: due to their higher mobility, electrons will move towards the rod, leaving behind them a positive space charge. This will cause an increase of the electric field at the region near the plane. It is as though the rod extended and the gap diminished.

If the rod is negative, when electrons flow away, positive charge will be left near the rod, increasing the field (easier corona) there, but reducing the ionization region into the gap, which demands a higher voltage to cause the flashover.

A good reference is the book High Voltage Engineering - Fundamentals (E. Kuffel, W.S. Zaengl, J. Kuffel), 2nd edition, pages 357 to 359.

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