Bus bar bracing 2

[hogdawg]

Can anyone help me with bus bar spacing for different kA bracing? I have a spread sheet with formulas but it seems way over kill. I thought that 21" between insulators was capable to withstand 65 kA but me table says it should 7" for single 1/4" x 4" bus!

Thanks,

 

[jraef]

Check this out, the answer may surprise you!

Powell Technical Brief #59

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[jraef]

D'oh! Sorry.
You said spacing and bracing in the same sentence, I only saw spacing. Bracing is a differnt matter. Disregard that paper as far as that is concerned.

Try these.
ANSI/IEEE Std. C37.20 Switchgear Assemblies Including Metal-Enclosed Bus
ANSI/IEEE Std. C37.23 for Metal-Enclosed Bus

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[hogdawg]

where did I goe wrong? I braced the bus bar on about 2 feet intervals meaning supported to frame front and back. I was referring to the distance between insulators. Most of our applications are low voltage, 480 down. The question is: Is there a table (other than the one I have) that will give me insulator centers based on bus sizes and spacing between buses edge up?

 

[asco1]

See UL 891 Supplement B.

It has a chart for between 42K & 100K, Max 4000A.

Example:800A-4000A, 65,000 @ 480V, bars edge-edge, min. 1" bar to bar, min. 5" center to center, 21" between supports.

Example:800A-4000A, 65,000 @ 480V, bars face-face, min. 4" bar to bar, min. 6" center to center, 48" between supports, 21" between braces.