# What exactly is a Bus?



## Phatso86 (Sep 13, 2016)

I am so confused as I never really understood what this means.

Given the attached circuit, where/what exactly is a bus ?

on a side note, what is an infinite bus. I googled this of course but do not understand what I find.

View attachment 8596


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## bcolwell3 (Sep 13, 2016)

There are four buses marked with triangles around them: 1, 2, 3, &amp; 4


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## Flyer_PE (Sep 13, 2016)

An infinite bus is one that has no limit on the amount of current it can supply at a given voltage.  In the circuit above, since Van1 is an ideal voltage source, Bus 1 is an infinite bus.


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## knight1fox3 (Sep 13, 2016)

Single-line representations of power systems as shown above are typically utilized to make analysis and per-unit calculations somewhat easier. This particular circuit appears to be a fairly typical distribution (bus 1) --&gt; step-up xfmr --&gt; transmission (buses 2 and 3) --&gt; step-down xfmr --&gt; utility distribution/load (bus 4)


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## Phatso86 (Sep 13, 2016)

knight1fox3 said:


> Single-line representations of power systems as shown above are typically utilized to make analysis and per-unit calculations somewhat easier. This particular circuit appears to be a fairly typical distribution (bus 1) --&gt; step-up xfmr --&gt; transmission (buses 2 and 3) --&gt; step-down xfmr --&gt; utility distribution/load (bus 4)


so each bus is shown as a small vertical line under a triangle. What purpose is there for having 2 and 3 so close?

What exactly is the bus even doing? Is it something that exists outside of this circuit?


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## knight1fox3 (Sep 13, 2016)

Phatso86 said:


> so each bus is shown as a small vertical line under a triangle. What purpose is there for having 2 and 3 so close?


Correct. And in reality, bus 2 and 3 are likely not very close at all. Transmission lines can span hundreds of miles. But in doing a circuit representation to perform calculations, there's no need to make them any longer than they need to be for a simple diagram.



Phatso86 said:


> What exactly is the bus even doing? Is it something that exists outside of this circuit?


A bus is strictly for power distribution. You could also think of it as a node. How does one get power from point A to point B? With a bus (i.e. over-head power lines that you see pretty much every where you go).


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## Phatso86 (Sep 13, 2016)

knight1fox3 said:


> A bus is strictly for power distribution. You could also think of it as a node. How does one get power from point A to point B? With a bus (i.e. over-head power lines that you see pretty much every where you go).


So what is a real world example?

One bus right outside my house that distributes power to my neighborhood? Or is it a power station which is miles away?

Can I think of a bus as a "battery" that receives power elsewhere and keeps it for distribution?


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## knight1fox3 (Sep 13, 2016)

Phatso86 said:


> So what is a real world example?
> 
> One bus right outside my house that distributes power to my neighborhood? Or is it a power station which is miles away?


Have a look at the image below to see if it helps out at all.


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## Phatso86 (Sep 13, 2016)

knight1fox3 said:


> Have a look at the image below to see if it helps out at all.
> 
> View attachment 8597


so which are the buses here?


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## knight1fox3 (Sep 13, 2016)

Phatso86 said:


> so which are the buses here?


Anywhere you see lines (i.e. like the power lines you see in your area) connected to a terminating point that then distributes to a component or structure.


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## cupojoe PE PMP (Sep 13, 2016)

A panelboard would be a bus. An MCC would be a bus. Literally everything where you make a connection is a bus, it is not a single piece of equipment, it is basically anything in the distribution that isn't a wire, load, transformer, etc.

What is it that you do and are not familiar with this stuff?


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## Phatso86 (Sep 14, 2016)

cupojoe PE PMP said:


> A panelboard would be a bus. An MCC would be a bus. Literally everything where you make a connection is a bus, it is not a single piece of equipment, it is basically anything in the distribution that isn't a wire, load, transformer, etc.
> 
> What is it that you do and are not familiar with this stuff?


I'm a structural engineer as shown here

&lt;&lt;&lt;-----


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## Ship Wreck PE (Sep 15, 2016)

knight1fox3 said:


> > 1 minute ago, Phatso86 said: so each bus is shown as a small vertical line under a triangle. What purpose is there for having 2 and 3 so close?
> 
> 
> Correct. And in reality, bus 2 and 3 are likely not very close at all. Transmission lines can span hundreds of miles. But in doing a circuit representation to perform calculations, there's no need to make them any longer than they need to be for a simple diagram.
> ...


Let's not forget about computer busses.


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## einatlanta PhD PE (Sep 15, 2016)

Getting down to what a power bus is, for a common application (there are infinite designs essentially) imagine a flattened 1/4 to 1/2 in thick piece of copper rectangular in shape. It is similar to say a structural member such as one of the concrete floors in a skyscraper.....all of the steel beams connected to the floor transmit a sum of the force to the floor and can redistribute to the beams below it. This is a simplified single phase image so a three phase image would be to have three buildings next to one another identical in force distribution. That's it.....all I got!


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## snickerd3 (Sep 15, 2016)

a bus is a large vehicle with the purpose of transporting many people from one place to another.


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## einatlanta PhD PE (Sep 15, 2016)




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## Phatso86 (Sep 15, 2016)

einatlanta PhD said:


>


wait,

so a bus is a vehicular device that mysteriously transports gay people from one rainbow to another?


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## KatyLied P.E. (Sep 20, 2016)

You may also see it spelled as "buss",  "buss bar", "bussbar", or "busbar" in some texts.  below is the Wikipedia definition which pretty much nails it:

"In electrical power distribution, a *busbar* (also spelled *bus bar*, or sometimes as *buss bar* or *bussbar*, with the term _bus_ being a contraction of the Latin _omnibus_, "for all", or _buss_ being short for _buttress_) is a metallic strip or bar (typically copper, brass or aluminium) that conducts electricity within a switchboard, distribution board, substation, battery bank, or other electrical apparatus. Busbars are used to carry substantial electric currents over relatively short distances; their greater surface area (compared to a wire of the same weight) reduces losses due to corona discharge. Busbars are not normally structural members."

Having said that in older substations or platn switchyards you may see large capacity conductor being used as bus.  In those situations it's commonly known as flexible bus.


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## Ken PE 3.1 (Sep 20, 2016)

KatyLied P.E. said:


> You may also see it spelled as "buss",  "buss bar", "bussbar", or "busbar" in some texts.  below is the Wikipedia definition which pretty much nails it:"In electrical power distribution, a *busbar* (also spelled *bus bar*, or sometimes as *buss bar* or *bussbar*, with the term _bus_ being a contraction of the Latin _omnibus_, "for all", or _buss_ being short for _buttress_) is a metallic strip or bar (typically copper, brass or aluminium) that conducts electricity within a switchboard, distribution board, substation, battery bank, or other electrical apparatus. Busbars are used to carry substantial electric currents over relatively short distances; their greater surface area (compared to a wire of the same weight) reduces losses due to corona discharge. Busbars are not normally structural members."
> 
> Having said that in older substations or platn switchyards you may see large capacity conductor being used as bus.  In those situations it's commonly known as flexible bus.


Strain bus is our words of choice for conductored busses.


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## knight1fox3 (Sep 20, 2016)

Should we add some complexity and start discussing load flow with slack, load, and generator buses? :dunno:


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## Supe (Sep 20, 2016)

knight1fox3 said:


> Should we add some complexity and start discussing load flow with slack, load, and generator buses? :dunno:


Man, you give a guy one master's degree...


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## P-E (Sep 20, 2016)

Not to be confused with a bus short...

short bus
A bus that people who can't spell derogatory take.
If you can't spell derogatory then you probably ride the short bus.


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