Electrical Engineering - Three-Phase Systems in Power Applications - Discussion

Discussion :: Three-Phase Systems in Power Applications - General Questions (Q.No.2)


In a three-phase system, when the loads are perfectly balanced, the neutral current is

[A]. zero
[B]. one-third of maximum
[C]. two-thirds of maximum
[D]. at maximum

Answer: Option A


No answer description available for this question.

Tamil said: (Aug 8, 2011)  
Please explain this ans.

Jyoti said: (Aug 24, 2011)  
At balanced state sum of currents of all phase ie- Ia+Ib+Ic=0 these currents are flowing through neutral so that its value is zero.

Vinoth said: (Sep 6, 2011)  
Thanks jothi.

Hussain said: (Sep 26, 2011)  
Good job jyoti.

Tushar said: (Jan 5, 2012)  
In balance condition, the total current equal to zero.

Lakshmiee02 said: (Feb 24, 2012)  
At balance cond. for 3pha sys Ia+Ib+Ic=0,which is the total current following throw the neutral point of 3pha sys.i.e. zero

Sohail Qaisar said: (Apr 3, 2012)  
Thanks lakshmiee.

Ravi said: (Apr 15, 2012)  
KCL, in a node sum of all currents is zero. So if we extract another line there is no chance of load drop. So no current flow.

Pavan.A said: (Oct 21, 2013)  
Yes, we apply KCL I(total) = I1 + I2 and I1, I2 are the load current and I (total) is the neutral.

Silambu said: (Jan 22, 2014)  
Sum of entering current = sum of leaving current.


S.Hari said: (May 2, 2014)  
Because of neutral current = I1+I2+I3 becomes zero.

Sandip said: (Jun 30, 2014)  
The sum of current = to load current. So it is zero.

Rajiv Gandhi said: (Nov 5, 2014)  
As per KCL law the sum of the incoming current is equal to sum of the outgoing current in a balancing circuit three phase system.

Prabhu said: (Nov 21, 2014)  
Memorized KCL.


i1+i2+i3 = i.

Srinivas said: (Apr 28, 2015)  
Here i = i1+i2+i3.

Hence i is neutral.

Biman Roy said: (Jul 25, 2015)  
At balance condition Ia+Ib+Ic=0. So neutral current becomes zero.

Nagaraju said: (Aug 17, 2015)  
In 3 phase system balanced currents is equal to ZERO.

Bhimesh said: (Dec 23, 2015)  
As a considered KCL law incoming currents are equal to outgoing currents so the system balanced condition (IR=IY=IB=0). In this condition considered the neutral current is ZERO.

Shankar said: (Apr 3, 2016)  
Yes, you are correct @Bhimesh.

Sanjeev said: (Apr 6, 2016)  
Since we have shown that the neutral current is zero we can see that removing the neutral core will have no effect on the circuit, provided the system is balanced. Such connections are generally used only when the load on the three phases is part of the same piece of equipment (for example a three-phase motor), as otherwise switching loads and slight imbalances would cause large voltage fluctuations.

Zeeshan said: (Jun 9, 2016)  
Hi, can you explain me for example line one 25 A & line two 65 & line three 40 how calculate what's amp neutral.

Rstar said: (Sep 13, 2016)  
It is balanced load so the neutral current is zero. We want proof to let do one thing remove the neutral core and observe the circuit there no different.

Bipin said: (Sep 18, 2016)  
The current flows through neutral when the load is unbalanced. In balanced state, Ia + Ib + Ic=0.

Surya said: (Nov 22, 2016)  
Thanks for all your explanation of the answer.

Ankur Yrigunayat said: (Mar 2, 2017)  
What is the neutral current?

Sangram Das said: (Apr 12, 2017)  
Here, Ia + Ib + Ic = 0.

Siddu said: (Aug 29, 2017)  
The sum of all the phase=0 so that's why neutral=0.

Beyene said: (Aug 21, 2019)  
Zero is the answer. Since Ia+ Ib +Ic=In=0.

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.