Current in the neutral wire of 3 phase system

When a 3 phase system is balanced, what will be the current in the neutral wire ?


  • ashuashi
    Practically there is no balanced 3 phase system. Ideally in 3 phase balanced system neutral current will be "ZERO".

  • avm
    I was also of your opinion. But i have seen in a book that the neutral current in a three phase balanced system is one third of the phase current. that is why i posed the question.

    thank you for reply
  • ashuashi
    This case is for Star connection & delta connection when Line current & Phase current come into picture.

    Check for phase current & Line current details. Your doubt will be resolved.
  • sauravgoswami
    first of all nuetral point is a null point,though it not an ground ,well theoritacally it should be ZERO,but practically its not possible so watever network you are considering you should try to keep it close to zero.
  • laxman7m
    Ideally, the current in the neutral wire is ZERO
  • ashuashi
    what are your views AVM. Did you find the answer to your querry?
  • avm
    Thank u all who have contributed to the discussion...............................
  • baja
    Neutral carries sum of three currents.
    In a 3 ph system currents whose magnitude and angle are
    1. I (0)
    2. I (120)
    3. I (240)

    if we add all three we get zero..
  • manoj_2all
    Neutral is the point at which all the three phase’s current meets and the algebraic sum of current becomes zero in case of “Balanced Load Condition”.

    I = I1 + I2 + I3 = 0

    When ALL phase has balanced load, neutral should be ZERO volt in respect to earth. Be careful the word “Balanced”, which means, if there is an unbalanced phased (due to load), the neutral will no longer be ZERO volt in respect to earth. When there is more than ZERO volt between neutral and earth, then there will be current flow through these 2 points (Leakage Current).

    Even for most of the time, neutral and earth has ZERO volt between them; they should never be connected together or be used interchangeably.

    Neutral: Return path of current flow in order to make a closed circuit [Return Path Conductor].

    Earth: Path for Leakage current [Short Circuit / Fault Current / Crack in Insulation] in the circuit to protect Human & Equipment Safety.
  • QuarkToo
    zero and there is no need for a neutral wire if it is truly balanced. The neutral wire keeps voltage spikes from occurring in an unbalanced system. It is unlikely that you will find a balanced system in the real world.
  • hetal prajapati
    hetal prajapati
    nutral is only in star connection no nutral wire in delta am right?
  • sasuke
    I [FONT="]though Ineutral = I1 + I2 + I3. and not zero. should have current as neutral are return path of the phase current right? [/FONT]
  • saurabh2486
    theoretically it will be 0 but practically it will show readings close to 0 as there might be some losses
  • prabim
    Why excessive neutral current dot desirable in power distribution systems?
  • debskolmodin
    If 2 currents on phase A and B are 16 A and phase C is 10 A what is the current on the neutral? Thanks in advance for your help.
  • narayana murthy
    narayana murthy
    If 2 currents on phase A and B are 16 A and phase C is 10 A what is the current on the neutral? Thanks in advance for your help.
    i think it may be 4 or 8
    because difference current flows in neutral to balance
  • Arp
    do the phasor sum of current not scalar
  • narayana murthy
    narayana murthy
    do the phasor sum of current not scalar
    i think yes is the answer
    as per my knowledge current lags voltage depending on load and each phase voltage is divided by 120 deg so current will be on same to the voltage
    but it does not same for all the voltages as type of load change in phases the angle is also changes respective to the voltages
    so there is some change in phase currents

You are reading an archived discussion.

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