Electrical Engineering - Three-Phase Systems in Power Applications - Discussion
Discussion Forum : Three-Phase Systems in Power Applications - General Questions (Q.No. 9)
9.
A two-phase generator is connected to two 90 
load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?
load resistors. Each coil generates 120 V ac. A common neutral line exists. How much current flows through the common neutral line?Discussion:
63 comments Page 2 of 7.
Ali said:
9 years ago
the correct answer is (B) as:
This is a two phase system gnerator with source voltage:
Va = 120 with zero angle & Vb with angle 90 degrees, thus the nutral current is as follows
In = Va /90 + Vb / 90 = (120/_0)/90 + (120/_90) = 1.33 + j1.33 = 1.88.
This is a two phase system gnerator with source voltage:
Va = 120 with zero angle & Vb with angle 90 degrees, thus the nutral current is as follows
In = Va /90 + Vb / 90 = (120/_0)/90 + (120/_90) = 1.33 + j1.33 = 1.88.
Ayush Kumar said:
9 years ago
It is simple question since, two phase generator is connected to two load resistor therefore resistance = 90 * 90 = 8100 & total voltage = 120 * 120 = 14400.
Therefore required current through common neutral line is = 14400/8100 = 1.77A.
Therefore required current through common neutral line is = 14400/8100 = 1.77A.
(2)
Ram T Shelke said:
1 decade ago
In two phase system assuming phase diff equal to 90, the resultant voltage across a given resistor,
SQ ROOT(120*120+120*120) =170V.
Therefore current through neutral = current through given resistor = 170/90 = 1.888A.
SQ ROOT(120*120+120*120) =170V.
Therefore current through neutral = current through given resistor = 170/90 = 1.888A.
KeerthiRaj said:
1 decade ago
@Mr Parveen Kumar and Mr Sandeep Wasnik:
Although your ideas were wrong, but I think you people even don't know how to calculate phase to phase voltage, if you don't know please keep quiet, don't post wrong things.
Although your ideas were wrong, but I think you people even don't know how to calculate phase to phase voltage, if you don't know please keep quiet, don't post wrong things.
V.aruna said:
1 decade ago
There are two loads, hence the current passes through both the rheostats.
The given voltage is 120v.
For finding current,
V = IR.
I = V/R.
Hence I = (120/90) + (120/90) = 1.33+1.33 = 2.66 amp.
The given voltage is 120v.
For finding current,
V = IR.
I = V/R.
Hence I = (120/90) + (120/90) = 1.33+1.33 = 2.66 amp.
Dawid Roos said:
1 decade ago
The answer should be B;
I = 120/90*1.414 = 1.88A since the currents are 90 degrees out of phase
Could also be written as I = 1.33+j1.33(rectangular form) = 1.88A @ 45 degrees(polar form).
I = 120/90*1.414 = 1.88A since the currents are 90 degrees out of phase
Could also be written as I = 1.33+j1.33(rectangular form) = 1.88A @ 45 degrees(polar form).
Ashish said:
8 years ago
For 2ac, both phases will be 90° apart. thus for 'i' instantaneous current, there will be -I current, means I current in opposite direction.
Thus resultant current will be zero.
Thus resultant current will be zero.
Yousuf Hasan said:
1 decade ago
Circuit diagram is must, you don't know how the two resistor are connected? (series or parallel). For the line current you should know the equivalent resistance seen by the line.
Mohammed Javed said:
1 decade ago
I think two loading rheostats are there. the current passes through two rheostats.given voltage is 120v(each coil).
v=ir
i=v/r
i=(120/90)+(120/90)=1.33+1.33=2.66 amp.
v=ir
i=v/r
i=(120/90)+(120/90)=1.33+1.33=2.66 amp.
Khizar hayat said:
1 decade ago
It is double phase you have simply to do is,
v = 120 and R = 90.
(120.120) = 14400.
(90.90) = 1800.
We have i = v/R = 14400/1800 = 1.77.
D is the correct answer.
v = 120 and R = 90.
(120.120) = 14400.
(90.90) = 1800.
We have i = v/R = 14400/1800 = 1.77.
D is the correct answer.
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