×
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

Switchgear / Panel Board Rating
2

Switchgear / Panel Board Rating

Switchgear / Panel Board Rating

(OP)
If the panel board is rated at 50kA @ 1s, what does it refers to?
The short circuit withstand rating which the assembly/structure can withstand for a short time.
(or)
The short time rating of the Main breaker (Icw in IEC).
(or)
The bus bar short time rating.

Is the SCCR rating in NEMA relates to the panel board assembly/structure rating?

RE: Switchgear / Panel Board Rating

TH SC rating in the panelboard primarily refers to the bus bar capability to withstand the dynamic forces (peak <1 sec) and thermal heat generated for 1 second.

Panelboards are designed to accommodate a wide variate of rating circuit breakers. However, The rating of the assembly (panelboard & circuit breaker) is driven by the lowest rating of the individual component.

See if the UL article below could help.

https://www.ul.com/wp-content/uploads/2014/04/ul_P...

RE: Switchgear / Panel Board Rating

Dear Mr NickParker
Introduction: If the panel board is rated at 50kA @ 1s, what does it refers to?
Q1. The short circuit withstand rating which the assembly/structure can withstand for a short time?, or
A1. It is dependent on what is included in the test. If the test [excludes] the main breaker, than the test is only the busbar assembly and the structure.

Q2. The short time rating of the Main breaker (Icw in IEC)?, or
A2. Usually the test includes a main breaker. In this case, the test includes the main breaker, busbar assembly and the structure for XkA Ys.
Note: The main breaker remain closed (i.e. with instantaneous trip defeated) for the complete short-time duration.

Q3. The bus bar short time rating.
A3. It is also possible to test the busbar assemble with busbar holders (in the open air) [without any structure]. In this case, the test covers only the short-time withstand rating of the busbar assembly and the busbar holders [excluding the structure].
FYI: Reference IEC 61439-x for detail in the IEC world.

Che Kuan Yau (Singapore)

RE: Switchgear / Panel Board Rating

The SCCR in a NEMA/UL panel will be (in practice) the short circuit rating of the lowest rated device in the equipment (when it was built). In olden days, this equipment had a published bus bracing rating. This is no longer shown on equipment nameplates, IIRC.

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! Already a Member? Login


Resources

White Paper - The Evolving Landscape of Commercial Battery-Powered Trucks
What’s driving the evolving landscape of truck electrification? What are the barriers, motivators and strategies for accelerating the electric transition? What insights and resources are available for today’s design engineers working to achieve industry disruption and evolution? For answers to these and other pertinent questions, read this white paper. Download Now
eBook - Rethink Your PLM
A lot has changed since the 90s. You don't surf the Web using dial-up anymore, so why are you still using a legacy PLM solution that's blocking your ability to innovate? To develop and launch products today, you need a flexible, cloud-based PLM, not a solution that's stuck in the past. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close