3 Phase 120VAC to 1 Phase 230VAC

Just to satisfy my curiosity a bit: where and under what circumstances does 120VAC 3phase appear in this world? Not is North America, I don't believe.
 
120/208 systems very common in N.A., especially in older facilities such as in commercial (restaurants, retail stores, etc.) and light industrial (small factories). 120 to neutral for 1 phase devices and 208 phase to phase for 1 phase and 3 phase loads as KB1GNI said.
 
The Plc Kid said:
No such thing anywhere.




I Beg to Differ.
Click to expand...


I beg to differ, almost every inner city building uses 208 3 phase with a neutral (older pre-1960 construction especially), that way they could have both 3 phase power for motors and 120 Vac for lighting without using heavy and expensive transformers. For those who measured it not knowing it was 208 3 phase they will find 120 vac to ground off of all 3 phases. So it is commonly referred to as 120 v 3 phase, even though it is actually 208 v 3 phase.
 
Page 1 doesn't answer the OP's question. Page 2 is becoming a statement of the obvious in the US. Are you guys really gonna burn another page arguing 120/208?
Please stop this, and answer the OP's question.
 
keithkyll said:
Page 1 doesn't answer the OP's question. Page 2 is becoming a statement of the obvious in the US. Are you guys really gonna burn another page arguing 120/208?
Please stop this, and answer the OP's question.
Click to expand...

thank you, op's question cannot be answered until he clears up the question of what his voltage is phase to phase. A transformer is called for, but what the primary voltage will be is questionable. as stated he can use a standard off the shelf control transformer for 230 to 120 vac hooked up with the secondary to 120 vac and outputting 240 vac. Just have to know how many KVA he needs, as that will always stay the same.
 
OP's question: How do you make 1-phase 230 from 3-phase 120?

Answer: use a transformer. BUT, you're going to have to answer my question to know which transformer to use...

MY question: Where are you finding 3-phase 120? Is that 70VAC phase to neutral, 120VAC phase to phase, or 117VAC phase to neutral, 208VAC phase to phase?

On this page is the discussion of 120/208. 208 really is NOT uncommon in the US. I've seen it in many plants during my 25 years of industrial experience. And Max is right -- it's VERY common for large industrial/commercial lighting/fixture circuits.

BUT -- that would properly be called 208 3-phase, not 120 3-phase. 120 3-phase would be 70V to neutral.
 
OK, this is about terminology. I'm OK with that. In my experience, three phase power is always expressed as the voltage phase to phase since, if the center of the wye is not grounded, you cannot predict the voltage to ground or neutral since it is floating.

208Y/120VAC I'm well familiar with.

Thanks for the clarification.
 
OZEE said:
...BUT -- that would properly be called 208 3-phase, not 120 3-phase. 120 3-phase would be 70V to neutral.
Click to expand...
Exactly. The OP is in India (location = mumbai). English is not the native language, so let's give him a break. Try to fill in the blanks. If the OP asked for 120/208 instead of 120...

Next is power in India. I see several high voltages for 3 phase from 380 to 415, 50 Hz. Even when I fill in the blanks, still not sure what he's trying to do.
 
maxketcham said:
I beg to differ, almost every inner city building uses 208 3 phase with a neutral (older pre-1960 construction especially), that way they could have both 3 phase power for motors and 120 Vac for lighting without using heavy and expensive transformers. For those who measured it not knowing it was 208 3 phase they will find 120 vac to ground off of all 3 phases. So it is commonly referred to as 120 v 3 phase, even though it is actually 208 v 3 phase.
Click to expand...

Now you got it right :D
 
There is no 120 3 phase. There is 208 3 phase. 208Y/120.

It is important to be correct here as this would confuse future members reading this thread that have limited knowledge on the subject.
 

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