×
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

Switch Fuse unit

Switch Fuse unit

Switch Fuse unit

(OP)
Is it possible to trip switch fuse unit via external trip signal? In other word does HV (22kv)switch fuse unit have trip coil?

RE: Switch Fuse unit

Hi HiSet:
         I have never seen a trip coil on a fuse unit assembly for 22 kv applications. I do not believe what you are inquiring about is possible.
         Is there an upstream switching device that can be modified for this application?

Good Luck.
Ang

RE: Switch Fuse unit

(OP)
It is about busbar proptection of HV(22kV) board ,where all circuits except station service transformer circuit have dedicated CTs for high impedance based bus protection scheme. Station service trf bay is switch fuse unit without CT. Appropriate fuse can be choosen to make sure that BZ scheme do not operate for external fault(i.e. on station service trf HV or LV side) but for real internal bus fault , how do you make sure that fuse blows to isolate faulty bus ?

RE: Switch Fuse unit

You have a few of options:

Replace the fuse/switch combination with a circuit switcher or circuit breaker. - Expensive

Add a motor operator to the fuse switch. - Sllooooowwww

Add a high speed ground switch after the fuse to ensure enough fault current to clear the fuse fast. - Make a little fault a big fault

Coordinate your bus protection with the fuses so that you'll never trip the bus for anything the fuse would clear.  Bus faults generally draw lots and lots of current while your fuse is probably pretty small. - Best option in my opinion.

RE: Switch Fuse unit

(OP)
David,
Thanks for that.Your last option seems most prudent but  how do you make sure that busbar  is physically isolated after genuine bus fault. All other circuits(CBs) will trip by virtue of trip signal emanating from Bus prot scheme but station service  bay will remain connected and potentially could back feed low amount of fault current (if there is a source to do so) on to the faulty bus

RE: Switch Fuse unit

Never seen a station services transformer that could back feed a faulted bus; never seen one with a source.  Not to say that it couldn't happen but you'd just have to make sure there was no source that could be switched in.

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