# "Three Phase Electric Power"



## al's4 (Aug 7, 2015)

Hi: I am well aware and thank you for the warning.


----------



## 480sparky (Sep 20, 2007)

You can either get the same amount of power for less wiring, or more power for the same amount of wiring.


----------



## papaotis (Jun 8, 2013)

never thought of it tat way, but that pretty much sums it up:thumbup:


----------



## al's4 (Aug 7, 2015)

*Three Phase Electric Power*



480sparky said:


> You can either get the same amount of power for less wiring, or more power for the same amount of wiring.


*Hi 480sparky: That sounds logically sound and I thank you; although, I was hoping for a theoretical and scientific explanation on how the phenomenal is accomplished.*


----------



## 480sparky (Sep 20, 2007)

al's4 said:


> *Hi 480sparky: That sounds logically sound and I thank you; although, I was hoping for a theoretical and scientific explanation on how the phenomenal is accomplished.*


Think of 3 cylinders in your car's engine.


----------



## 99cents (Aug 20, 2012)

480sparky said:


> Think of 3 cylinders in your car's engine.


That's a very good comparison. The concept of time is very important in understanding three phase.


----------



## al's4 (Aug 7, 2015)

*Three Phase Electric Power*

*Hi: Would you care to elaborate? Does it have anything to do with the sine wave? I remember that in my study of rectifiers we studied half wave and full wave, the latter doubling the output of the first. Is it something similar?*


----------



## Pharon (Jan 20, 2014)

Yes, it has everything to do with the sine wave.



> Another way to look at 3-phase power is as a combination of three single-phase circuits that deliver power in a way that it never falls to zero, meaning that the load is the same at any instant (the concept is easy to grasp when you look at the waveform).
> 
> Because the load is constant, 3-phase power is ideal for motors—it eliminates the need for starting capacitors. It also allows for smaller wires (i.e., less copper) and lower voltages for the same power transmission as single-phase, making it less expensive and safer.
> 
> http://www.belden.com/blog/datacenters/3-Phase-Power-Wye-It-Matters.cfm


----------



## eddy current (Feb 28, 2009)

1. In 3 phase, the power never falls to zero on the sine wave. Single phase it falls to zero 3 times every cycle. Basically the power to the load is the same at any instant in time.
2. HP rating of motors and KVA rating of transformers are 150% greater than single phase motors and transformers of the same size.
3. In a balanced 3 phase system the conductors need only be 75% the size of the conductors needed for a single phase system of the same KVA rating.


----------



## al's4 (Aug 7, 2015)

Hi: My thanks to all of you, in particular, to eddy current and to Pharon for and in depth analysis of the system.


----------



## RIVETER (Sep 26, 2009)

al's4 said:


> *Hi everyone: I have got a question which I always wondered about; it concerns three phase electric power. "How is the power saving characteristic of three phase electric power wiring accomplished.*


Why are all of the letters BOLD? Anyway, if the question is serious it is because three phase is more efficient. As one phase goes towards current zero another is edging upwards much as an automobile engine when one cylinder is beyond " TOP DEAD CENTER" and is going in the other direction another cylinder is "on it's way".


----------

