Economic Advantages and Disadvantages Three Phase Compared to Single System

[RiCkRuD3]

What are the economical advantages and disadvantages of using a three phase distribution system compared to a single phase system?

 

[Jamzie]

What are the economical advantages of asking a homework question compared to performing research and self study? None, not on this forum anyway.

 

[oldtimer]

It has nothing to do with advantages it is to do with the transmission of electricity in 3 phase format ie L1-L2-L3 or in this country what used to be Red-Yellow-Blue.

Plus it is all to do with size ie big building needs 3 phases as most of the plant ie AHU,chillers,pumps will be 3 phase load as single phase would not be an option.

So go into a domestic setting funny enough its still a 3 phase transmission but when you get out on the road it is split into single phase so 3 houses in a row on is fed from Phase L1 then the other is L2 then the last is L3. So in a house you may think you are a single phase load but you are in fact part of a 3 phase supply.

Now in a street if you lose a phase funny enough it will be every 3 house that loses its power So in other words in a domestic situation single phase is ok but when you are into commercial industrial then 3 phases.

Also noted you are from the US so not sure but because you transmit your power as 115vac then for big loads ie electric cookers then they will have a 2 phase or 240vac supply (happy to be corrected here)

 

[Outspoken]

What are the economical advantages and disadvantages of using a three phase distribution system compared to a single phase system?

Do you want to be a little more specific, most of the economic advantages and disadvantages are connected to the location of the supply and the type of installation your putting it into.

In larger installations 3 phase clearly has an advantage because it is easier to moderate/account for power factor and thus reduce the loads on the supply, because poor power factor impacts the load drawn from the supply and thus costs the end user money. Further, 3 phase motors for plant are far more efficient and economic for a given size than single phase units, they draw less load from the installation and thus the actual installation costs are reduced...

If you actually do some thinking I am sure you can establish the answer to your question yourself.

 

[somersetsparks]

It has nothing to do with advantages it is to do with the transmission of electricity in 3 phase format ie L1-L2-L3 or in this country what used to be Red-Yellow-Blue.

Plus it is all to do with size ie big building needs 3 phases as most of the plant ie AHU,chillers,pumps will be 3 phase load as single phase would not be an option.

So go into a domestic setting funny enough its still a 3 phase transmission but when you get out on the road it is split into single phase so 3 houses in a row on is fed from Phase L1 then the other is L2 then the last is L3. So in a house you may think you are a single phase load but you are in fact part of a 3 phase supply.

Now in a street if you lose a phase funny enough it will be every 3 house that loses its power So in other words in a domestic situation single phase is ok but when you are into commercial industrial then 3 phases.

Also noted you are from the US so not sure but because you transmit your power as 115vac then for big loads ie electric cookers then they will have a 2 phase or 240vac supply (happy to be corrected here)

As far as I know oldtimer, I believe the americans generally use the 'Edison hotwire' system, which is very much like our split phase arrangement, which is really single split phase, 2 phases of 11kv in, split single phase out with 240v between phase/neutral and 480v between the two phases. Obviously theirs is 115v/230v ish. However I assume they still derive this from a 3 phase HV network?

 

[Outspoken]

As far as I know oldtimer, I believe the americans generally use the 'Edison hotwire' system, which is very much like our split phase arrangement, which is really single split phase, 2 phases of 11kv in, split single phase out with 240v between phase/neutral and 480v between the two phases. Obviously theirs is 115v/230v ish. However I assume they still derive this from a 3 phase HV network?

Thats how I remember it from when i worked over there more than 2 decades ago, so I don't think it changed, and this site is full of such useful information for US/Canadian based sparks

 

[Engineer54]

There nominal domestic type supply is 3 wire single phase 240V/120V. So your ''ish'' is right!! ..lol!!

 

[somersetsparks]

There nominal domestic type supply is 3 wire single phase 240V/120V. So your ''ish'' is right!! ..lol!!

I'm not a fussy man me!