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If the load is connected in wye (star) and it has a neutral, then the vectorial-difference of the phase currents will flow in the neutral and there will be no problem. On the other hand, if there is no neutral, then an unbalanced load would cause unbalanced phase voltages.
For a perfectly balanced load, with identical loads connected between each line conductor and the neutral conductor, there should be no neutral current. This is because the vector sum of three identical current, displaced by 120o, is zero.However, for an unbalanced load, there will always be a neutral current because the vector sum of the currents will not cancell.
As normally load distribution is done equally in all three phases, almost balanced current is drawn by load and current flow though neutral is very small when compared to the phase and hence difference in cable size is observed
Simply because it is cheaper. (You dont need the extra wire) However you can only use a 3 wire system if the load is a balanced load. If the load is not balanced you need the fourth wire (neutral/return) to take the out of balance current.
A delta-connected system is described as being a three-phase, three-wire, system, and doesn't have a neutral. But a balanced star (wye) connected load (e.g. a three-phase induction motor) doesn't actually require a neutral.
I think you probably mean is a neutral conductor necessary for a balanced star-connected load? If this is what you mean, then the answer is no, it isn't, as the phasor-sum of the phase currents will equal zero. Often, though, it is difficult to achieve a balanced load, so a neutral is then necessary, as it is needed to provide a return path for the unbalanced current -without this neutral, the phase voltages would change and become unbalanced.
By having a balanced load
Balanced load means no unbalanced currents, so the neutral current should be near zero.
if it is balanced then neutral current is zero (!,e iR=iY=iB).AnswerFor both a balanced and an unbalanced load, the neutral current will be the phasor sum of the line currents.
If the load is connected in wye (star) and it has a neutral, then the vectorial-difference of the phase currents will flow in the neutral and there will be no problem. On the other hand, if there is no neutral, then an unbalanced load would cause unbalanced phase voltages.
For a perfectly balanced load, with identical loads connected between each line conductor and the neutral conductor, there should be no neutral current. This is because the vector sum of three identical current, displaced by 120o, is zero.However, for an unbalanced load, there will always be a neutral current because the vector sum of the currents will not cancell.
As normally load distribution is done equally in all three phases, almost balanced current is drawn by load and current flow though neutral is very small when compared to the phase and hence difference in cable size is observed
Simply because it is cheaper. (You dont need the extra wire) However you can only use a 3 wire system if the load is a balanced load. If the load is not balanced you need the fourth wire (neutral/return) to take the out of balance current.
A delta-connected system is described as being a three-phase, three-wire, system, and doesn't have a neutral. But a balanced star (wye) connected load (e.g. a three-phase induction motor) doesn't actually require a neutral.
If a neutral breaks the load will cease to operate.
No. In North America you are billed on the consumption of watts (amps x volts). Both legs L1 and L2 are monitored inside the watt-meter that is situated on the side of your house and are independent from the unbalanced or balanced load on the neutral.
For a balanced three-phase load, the neutral current is zero, so the loss of the neutral would have no effect.However, for an unbalanced load, the 'difference' between the line currents results in a neutral current.So, for an unbalanced load, if no neutral current can flow, then the load's neutral point will no longer remain symmetrical, and the line voltages will become unbalanced. If the unbalance is severe, then individual loads may be subject to over-voltages or under-voltages.