ELECTRICAL BUSBAR SIZING

An electrical bus bar is defined as a conductor or a group of conductor used for collecting electric power from the incoming feeders and distributing them to the outgoing feeders.
Busbars are generally made of Copper or Aluminium.
An undersized busbar will result in excessive heating of the busbar under normal operating condition, leading to rise of temperature beyond permissible limits.
While, an oversized busbar will lead to a costly switchboard.
Major factors affecting Busbar Sizing are
Voltage and Current rating of the system
Enclosure Ingress Protection rating
Forced ventilation or natural ventilation
Working and ambient temperatures
Heat loss by convection and radiation
Heat generated in the busbar
Busbar current rating is normally defined as below:
1. Continuous Current rating
2. Short-circuit Current rating
Continuous Current Rating is the amperes that a Busbar will carry continuously in free air without exceeding the temperature limits. Continuous Current rating is expressed in Amperes (A).
Whereas, Short-circuit current rating is the maximum current a busbar can safely withstand for a specified time (such as 1 second or 3 Seconds). Short-circuit current rating is expressed in kilo-amperes/Sec (kA/Sec).

[@wesleygnanaraj8229]

Nice

[@shavaizkhan8165]

Please keep making such videos your videos are excellent

[@theelectricalsolutionschan1095]

Thank you, I will

[@ramjiram4867]

Very insightful informative video brother. Thank you very much.

[@theelectricalsolutionschan1095]

Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends.

[@prakashsatapathy1034]

Awesome. Please make a video on diesel generator sizing

[@theelectricalsolutionschan1095]

Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends. Videos on the above topic under preparation and will be uploaded shortly.

[@ganapathypv6587]

Very well explained easy to calculate. Thanks🙏

[@theelectricalsolutionschan1095]

Thanks. Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends.

[@rizalinotormis5447]

i think coeffecient k1 is mistakenly calculated. if e=10mm and a=120mm then e/a=0.0833, therefore, k1 should be 1.76 or 1.8?

[@theelectricalsolutionschan1095]

Thanks.
Yes, you are correct. The value of e/a has been erroneously calculated as 0.12 instead 0.08. Hence value of K1 will have to be changed accordingly.
Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends

[@josephansah5121]

Does the length of bus bar determined current it will carry or the thickness of bar determine the current it will carry. Thank you

[@theelectricalsolutionschan1095]

Thanks for your comment. No, Busbar length doesn't determine the current capacity. However, thickness of the busbar is one of the major factors which determines the current capacity.

[@mariomamani5692]

What standar (ANSI or IEC ) is the base of Busbar Rating?

[@theelectricalsolutionschan1095]

Busbar rating is based on busbar property (Cross-section, No of parallel busbars, section profile, support spacing, etc.) and not on any particular standard.

[@noname-ug2qx]

Short circuit calculation upto the busbar is incorrect. Impedance of the incomer, transformer and cable should be considered. Other than that, the concept if informative.

[@theelectricalsolutionschan1095]

Thanks for your comment. The Short Circuit calculation used in the example is a short cut one and neglects all impedances except transformer impedance. This will result in the maximum fault current that will be seen by the busbar as explained in the video.

[@iroshanlahiru609]

Bus bar current capacity 630A , its according Thumb calculations suitable 50*10 , but standard chart show 50*5 Which is correct ?

[@theelectricalsolutionschan1095]

Thumb rule calculation will give you a very high Busbar cross section as it based only on current density of the busbar material. But actual busbar sizing requires taking into account various other factors as explained in the video.

[@itachiiQuang]

Can your gave to me the document iec or ieee or evelent ? Pls help me

[@theelectricalsolutionschan1095]

Thanks for your comment. IEC & IEEE standard references are indicated in the video. These standards can be bought from various sources. However, copying and distribution is not allowed.

[@MrPcwortex]

Great video. I'm trying to find information about the minimum distance between copper bars with different potentials depending on voltage. Maybe you know where I can find this information?

[@tamjidkabir1543]

I have watched all the tutorials in your channel. Great contribution to the engineering community. Highly appreciated...❤❤

[@kittipotkaewnade5113]

From the video, after calculation you use only continuous current to consider busbar size. What about short-time withstand current? Do we also need it to consider busbar size?

[@theelectricalsolutionschan1095]

Thanks for your comments.
Once the busbar rating is decided (continuous and short circuit rating), the Continuous current rating is used for deciding the busbar cross-section.
Glad that you found the video useful. Please let me know your comments on my other videos. Please do subscribe to my channel and share with your friends.

[@uuday9093]

Very informative video with lucid explanation! 👍 Looking forward to more videos.

[@theelectricalsolutionschan1095]

Glad you liked it!

[@ganesha_pandiyan247]

Hello Sir, is this busbar calculation applicable for HV traction battery's Cell to cell and module to module busbars??

[@jhontejada5773]

Very intelligent ; i cannot see this approach in my prevuous studies all things is new for me...good job man!!!

[@mandardahi]

Thanks for informative video. We refer K.C. Agrawal's book for busbar sizing in which skin and proximity effects, busbar supports also are taken into consideration. What is your take on this ?

[@theelectricalsolutionschan1095]

Thanks for your comments. Skin effect and proximity effect do influence the busbar size. These effects basically increase the impedance of the conductor which in-turn reduces its current carrying capacity. Impacts of these effects are captured through the Conditions Co-efficients K1 & K3 in the MELSON and BOTH formula. Busbar supports design and distance between the supports are designed based on the short circuit rating of the busbar and not the other way around. Accordingly, once the Electrical rating is finalized, the supports and gap between can be designed (this is mostly carried out by the Panel manufacturers).

[@mandardahi]

@@theelectricalsolutionschan1095 Thanks for the clarification