×
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

LV MCCB and PCB Line-Ground Current Interrupting Capacity

LV MCCB and PCB Line-Ground Current Interrupting Capacity

LV MCCB and PCB Line-Ground Current Interrupting Capacity

(OP)
HI all,

UL 489 have sets of test currents associated with LV MCCBs and PCBs at full voltage rating. IEEE Std. 1015 also mentions single pole interrupting but not too much details were given. In UL 489, the test currents were set and ratings are minimum to obtain UL certification.

In short circuit calculations, line-ground faults are based on line-neutral voltages. IEEE 551 and 141 considers bolted three phase faults as basis for kAIC ratings for LV MCCBs and PCBs. However, these kAIC ratings are based on 3 poles operating and perhaps not based on 1 pole.

Line-ground faults in solidly grounded systems will pickup one MCCB pole as the currents are unbalanced and MY QUERY would be on cases where the line-ground fault current are GREATER than the 3 phase fault (in generator MCCB/PCB or immediately near the transformer secondary terminals.

QUERY: In cases where the line-ground fault is greater than the 3 phase fault and considering UL 489, does the kAIC now based on line-ground fault current and not the 3 phase fault current? How do we specify kAIC if the single pole kAIC is not even indicated in the MCCB nameplate?

Regards,

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