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If single phase power is 220 volts, why is 3 phase 440 volts and ...
https://www.quora.com/If-single-phase-power-is-220-volts-why-is-3-phase-440-volts-...
Nov 21, 2015 - Single phase voltage means voltage between line and neutral. So it is a 220 volt which is approximate value. But in power system genreally ratings are line to line so in 3 phase system 440 is line to line Rms voltage which is obtain by multiplying a factor of 1.732.
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If single phase power is 220 volts, why is 3 phase 440 volts and not 660?
77 Answers
Rishabh Sharma, Junior Technical Associate at ITC Limited (2017-present)
Originally Answered: If a single phase is 220V, why is three phase 440V, and not 660V?
I'll try to explain the way you would like if i am understanding your question well. But before that just keep few things in the back of your mind that
1. Voltage id the difference in potentials bw two points
2. singlephase voltage is the voltage between a phase and neutral. While the 3 phase is between any two out of those three phases.
3. Now all the 3 phases i.e ( 3 cables in the 3 phase supply ) have the same max rms (for undestanding you take it as avg.) value. i.e if you take any of the phases and check its voltage against neutral it will come 220 or 240 or so. But when you take the voltage between one phase to the other then it becomes 440.
4. Consider one sin wave that has max amplitude of 220 wrt its axis. So be it in positive cycle or in -ve it can go to a max of 220 (+220 or -220)
5. While in case of 3 phases the voltage can be used between two phases instead of one phase and neutral. So there are 3 phases but the catch is that you can calculate voltage between two points. Be it three phases but u can calculate volte between any two of them at a time. And the max voltage that you can get from any two phases is when one is at top of its positive cycle (i.e.+ 220) and the other at lowest of its negitive cycle (.-220) and what happens if you check voltage (potential difference) between these two points ((+220)-(-220)=440)
And this is the max that you can reach by comparing any two points in any of the phases wrt each other.
Yes if you have three phase supply produced at rms value of one phase 330V then you can get 660 but ony from any two phases of the three.
I've tried to be as simple as I could. I hope it clears some air.
