Supporting Upper and Lower Bus in Stations

[HarvCLAUtilities]

I am reviewing a 138kV station design with a upper and lower 3" alum. bus. Normally to connect the two bus together we use 2 split angle 2" bus in a "v" form. This design however has a single 3" vertical connection. My question is will this weaken the overall bus and cause concern for vibration or is there no difference structurally.

 

[jghrist]

The single vertical connection doesn't provide very much transverse support to the top bus. If there are sufficient supports other than at the crossing of upper and lower buses, then this would be acceptable. You can probably make a less expensive bus design using A-frames and fewer supports.

 

[Marmite]

A busbar system should be designed with adequate support and bracing to cope with the forces developed under short circuit conditions.
The attached file which is taken from the ABB switchgear manual gives some insight on the calculations required.
Regards
Marmite

 

[apowerengr]

I prefer that the A-frames have the same bus size as the main bus - it helps with inventory and a little extra capacity does not hurt. As stated, calculation for fault current forces are available. IEEE 605 addresses bus design in substations.