×
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

Recloser by passby protection
2

Recloser by passby protection

Recloser by passby protection

(OP)
To protect faults on our MV long distribution lines we use reclosers to see end of line faults. The questions is what is the protection practice when the reclosers are in the bypass mode for repair or maintenance and the back up protective device cannot see the end of the line fault.. Is exposure acceptable or are temporary fuses installed? If exposure is acceptable is there an acceptable time limit for exposure?

RE: Recloser by passby protection

Use a fused bypass.

RE: Recloser by passby protection

(OP)
That is done very often. The issue becomes the time, (using line crew), it takes to install temporary fuses versus just using the reclosure bypass blades when the maintenance time for testing the controls is very short. Does anyone accept that kind of exposure.

RE: Recloser by passby protection

2
Every part of the system should be covered by two different protective devices. So for any given recloser on the line, the upstream recloser or feeder breaker should always reach through the recloser in question and cover the entire line out to the next device beyond the recloser. This may be yet another recloser or may be multiple tap fuses. Having only one device that can sense a fault and trip for it is very risky. The upstream device will generally be slower than the recloser in question, but it may have tagging capabilities that would turn on an instantaneous trip and block reclosing to provide additional protection for the personnel working on the bypassed recloser.

RE: Recloser by passby protection

Fuses are the best option. good engineering practice is that reclosers that may cause protective issues when bypassed should have a cutout installed instead of a solid blade disconnect. That way a fuse may be inserted in bypass mode. Up to a 200amp T, K, ect fuse may be used as this is what most cutouts max out at. You will lose auto reclose function, but you will not have any high level faults going unnoticed.

RE: Recloser by passby protection

you can also switch some downstream sections to a different feeder and the rest will be covered by breaker protection

RE: Recloser by passby protection

(OP)
Our practice is to have a maximum of 3 sec to clear end of line faults. Keeping in mind no alloweed equipment damage allowed. What no one is sure about is where that number came from. The REA has some comments to allow up to 20 sec to clear end of line faults. What is the practice, i.e. accepted allowed time, to clear end of the line faults by utilities in normal conditions or in the condition when a recloser is being bypassed.

RE: Recloser by passby protection

On a short line its easy to allow the substation breaker to take over, but long lines especially where the conductor slims down are a challenge. Plus you dont want a fault to trip a main feeder during a re closer bypass. Good point, pwtran, if the feeder has other sources after the recloser in question those can be of help.

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