Three Phase Connection problem

[kane]

I am trying to implement a single phase load into the three phase circuit.
As the three phase circuit requires the balancing load among the three phase line L1,L2,L3, is it possible to design a circuit to implement the single phase load into the three phase line to fulfill the connection requirement?
Thanks for ideas and really appreciate your help!

 

[Dennis Alwon]

I have no idea what you are asking. Maybe you can explain better or maybe someone else will catch your meaning

 

[hillbilly1]

Three phase circuits do not have to be balanced, unless that is a design requirement. If you have three equal single phase loads, you can balance them by alternating the phase connections.

 

[Sierrasparky]

Welcom to the Forum

Can you please explain a bit better what you ask.

 

[Smart $]

I am trying to implement a single phase load into the three phase circuit.
As the three phase circuit requires the balancing load among the three phase line L1,L2,L3, is it possible to design a circuit to implement the single phase load into the three phase line to fulfill the connection requirement?
Thanks for ideas and really appreciate your help!

You are not required to precisely balance the load. However, all ratings associated with the higher than average line currents must be compliant. For exampe, you cannot calculate a 208Y/120 3? load at say 36kVA and have 100A ratings on all lines if the system is unbalanced, say 120A, 90A, and 90A on the associated lines.

 

[liquidtite]

if you have a 3 phase system 120/208 and your only using one leg and a nuetral say for a receptacle is that circuit called a singlephase ckt or is it still 3phase?

 

[gar]

130205-1953 EST

kane:

Use a 3 phase motor to drive a single phase alternator.

As others said provide more information on your problem.

.

 

[Smart $]

if you have a 3 phase system 120/208 and your only using one leg and a nuetral say for a receptacle is that circuit called a singlephase ckt or is it still 3phase?

Two-wire circuits can only be single phase circuits.

 

[liquidtite]

what about if you use two legs out of the three is that a single phase crk?or do you have to use al three legs

 

[GoldDigger]

what about if you use two legs out of the three is that a single phase crk?or do you have to use al three legs

If you have a three-phase source with a neutral (such as from a Wye secondary with neutral or from POCO) you can connect a single-phase (two terminal) load either from Line to Line on the supply or from Line to Neutral, with different voltages.
If you have some other three-phase supply, you can only connect from phase to phase.
You are not required to use all of the phase wires. But if it is large load, or there are many of them, you need to balance the total load across all three phases by selecting which phase wires to connect each of them to.

If as in your example you connect a receptacle to only one phase and the neutral of a 208/120 wye system, then that indeed a single phase load.
If the distribution system was designed for balanced loads, connecting a very large single phase line-to-neutral load may overload the neutral conductor.

 

[Smart $]

what about if you use two legs out of the three is that a single phase crk?or do you have to use al three legs

As I said previoiusly, a two-wire circuit can only be a single phase circuit. GoldDigger went into more detail on specifics.

FYI, there is an oddity that is dubbed 120/208V 1? 3W, which is generally a three-wire supply feeder consisting of two legs and a neutral "branched" from a 208Y/120 3? 4W system. Not uncommon for multi-dwelling units with a 3? service. This 120/208V supply is dubbed 1? because you can only connect standard single phase loads to it. Generally you want these supplies in multiples of three (A-N-B, B-N-C, and C-N-A) but there may be an odd one or two when balancing is not feasible... such as when four, five, seven, eight, ten, eleven, etc. apartments are fed this way.

 

[copper chopper]

is he just asking about how to hook up a phase converter ?

 

[GoldDigger]

is he just asking about how to hook up a phase converter ?

No. Or at least he does not seem to be. Very little point to it if he is.

 

[spark master]

He's from asia, so there is no 120volts

 

[iceworm]

I am trying to implement a single phase load into the three phase circuit.
As the three phase circuit requires the balancing load among the three phase line L1,L2,L3, is it possible to design a circuit to implement the single phase load into the three phase line to fulfill the connection requirement?

As others have noted: Yes, it is mostly a matter of money.

Can you please explain a bit better what you ask.

And it is a matter of design constraints. For example:
How much single phase power is needed?
How close does this have to balanced on the 3 ph side?

130205-1953 EST

Use a 3 phase motor to drive a single phase alternator..

Another method is to use a UPS - 3 phase rectifier, single output.
Expensive but workable.

ice

 

[Electrician2000]

if you have a 3 phase system 120/208 and your only using one leg and a nuetral say for a receptacle is that circuit called a singlephase ckt or is it still 3phase?

Single phase.