×
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

TCC plot reference voltage

TCC plot reference voltage

TCC plot reference voltage

(OP)
Hello,

Suppose I have a 3-phase 480V panel which has 277V branch positions. Is it correct that the TCC plot reference voltage should
be 480V? I am trying to plot a branch circuit breaker and am unsure if it should be 277V or 480V. Will a single pole single phase breaker off of such a panel see the 480V fault current?

Thanks.

RE: TCC plot reference voltage

Use 480V. It is a 480V/277V system. Fault current is the same. The breaker overcurrent trip unit cannot tell if it is a 480V phase-phase fault or a 277V phase-ground fault. It is the same trip curve whether it is a 30A three-pole or a 30 Amp single pole breaker.

The curve drawing software might incorrectly move the curve by a 1.732 factor if you enter 277V for the base. Try it and see.

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