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What is a neutral wires' function?
To carry the unbalanced load current.
What is the limit or range of the neutral current in an unbalanced three phase system for it to be regarded as faulty?
The limit or range of the neutral current in an unbalanced three phase system is the third harmonic in single phase non-linear load current is the major contributor to neutral current.
How do you find neutral current in star connected circuit?
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.
What happens if neutral of three phase four wire system is break?
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.
Is there an advantage of having a neutral wire in an unbalanced electrical system?
A neutral wire is essential in a three-phase star (or wye) connected system supplying an unbalanced three-phase load. Without a neutral, the voltage across each of the loads may become unbalanced, too.
How much will neutral current be in a 3phase 4-wire y system with a balanced load?
Balanced load means no unbalanced currents, so the neutral current should be near zero.
What are the applications of milliman's theorem?
One application is to determine the neutral current in an unbalanced wye (star) connected load.
Is there a current in star connected transformer in neutral side?
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.
Documentation of the Cancellation of the neutral current in unbalanced three phase four wire nonlinear distribution systems?
Different types of non-linear loads are expected to proliferate into the distribution system, causing the harmonic distortion levels on these systems to increase. Third harmonic and all other triplen harmonic currents have little diversity among different loads and add in the neutral. The neutral current in a low voltage three-phase four-wire distribution system is expected to increase resulting in significant problem The factors that affect the neutral current magnitude as well as the phase currents distortion are investigated. Neutral current suppression methods are presented in order to cancel the neutral current and improve the overall system distortion levels. In this project will insist in the solution that is based on the modified active power filter. The active power filter drastically improves the system performance and substantially reduces the neutral current.
Why can the neutral wire diameter be reduced in relationship to the phase wires?
The Neutral wire should be the same gauge and size of the phase wires. Only the Earth or Equipment wire can be smaller than the phase(hot) wires. <<>> On a three phase four wire distribution system the neutral can be reduced in size. The neutral only carries the unbalanced load current and should be sized to that current. The highest current load to neutral of the three legs is used to calculate the neutral sizing. There is no reduced neutral allowed on discharge lighting and non linear loads. A demand factor of 70% shall be permitted to be applied to that portion of the unbalanced load in excess of 200 A.
Can the neutral conductor be downsized in a 3 phase electrical system?
Yes, you can reduce the neutral in a three phase system. you must figure the unbalanced current the neutral will carry and also make allowances for any harmonics that may be present.
Does neutral wire carry voltage in a closed circuit?
The ground wire should carry no current at all, it is there in case of a short circuit to carry the (short circuit) current back to the breaker panel to trip the breaker. The neutral will carry the unbalanced load current between the 240 volt legs. e.g. L1 and N (neutral) 120 volts the load draws 8 amps. L2 and N (same neutral) 120 volts the load draws 12 amps. The difference between the two amperages is what the neutral will carry 12 - 8 = 4 amps.
