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.
Manivel said:
1 decade ago
Consider two coils which are connected to the terminals A and B respectively. The other end of the coils terminated in neutral point N.
Since, Emf generated in each coil is 120 then current Ian (flows from A to N) = 1.33(120/90) and Ibn = 1.33(120/90).
Hence, the current in neutral wire is 1.33+1.33 = 2.66 A.
Since, Emf generated in each coil is 120 then current Ian (flows from A to N) = 1.33(120/90) and Ibn = 1.33(120/90).
Hence, the current in neutral wire is 1.33+1.33 = 2.66 A.
Somnath said:
1 decade ago
I think it's 2.66.
2 phase generator. So connect load of 2*90 ohm resistance in parallel.
Resultant resistance will be 45.
Then I = V/R.
= 120/45 = 2.66 A.
2 phase generator. So connect load of 2*90 ohm resistance in parallel.
Resultant resistance will be 45.
Then I = V/R.
= 120/45 = 2.66 A.
Hami said:
1 decade ago
I think 1.88 A is right answer. Because there is common neutral wire which means 1.33 A. After multiplying with 1.141, we get 1.88 A.
Kalai said:
1 decade ago
Parallel connection, voltage same v = 120 v, R = 45 v, I = 120/45 = 2.66 A.
Vjagannadharao said:
1 decade ago
Resistance will be 45.
And I = V/R.
V = 40, i = 120.
I = 120/45 = 2. 66 A a write method.
Current neutral wire is 1.33+1.33 = 2.66 A.
Then I = V/R = 2.66 A.
And I = V/R.
V = 40, i = 120.
I = 120/45 = 2. 66 A a write method.
Current neutral wire is 1.33+1.33 = 2.66 A.
Then I = V/R = 2.66 A.
Chandrima said:
1 decade ago
Answer should be 1.88 amp.
V/i = 1.33 amp, current flowing through neutral 2*1.33 = 2.66, but RMS value of the current will be 2.66/sqrt2 = 1.88 amp.
V/i = 1.33 amp, current flowing through neutral 2*1.33 = 2.66, but RMS value of the current will be 2.66/sqrt2 = 1.88 amp.
NASR said:
1 decade ago
Right answer is D because:
1 = 120/90a with angle 0+120/90 with angle 120.
= 1.33+j0-0.665+j1.152.
1 = 120/90a with angle 0+120/90 with angle 120.
= 1.33+j0-0.665+j1.152.
Vijay yadav said:
10 years ago
I am correcting answer of @Mr Rasood.
I = 120/90*1.414 = 1.88 A since the currents are 90 degrees out of phase.
Could also be written as I = 1.33 + j 1.33 (rectangular form) = 1.88 A at 45 degrees (polar form).
= 1.88*cos 45.
= 1.88*1/square root (2).
= 1.88/1.41 = 1.33.
I = 120/90*1.414 = 1.88 A since the currents are 90 degrees out of phase.
Could also be written as I = 1.33 + j 1.33 (rectangular form) = 1.88 A at 45 degrees (polar form).
= 1.88*cos 45.
= 1.88*1/square root (2).
= 1.88/1.41 = 1.33.
Palthur said:
1 decade ago
In a two phase system voltages are displaced apart from each other by 90 degree so resultant of 2 currents flow through the neutral wire which is 1.88 A.
Awesome said:
9 years ago
@Amjad.
How have you done this. Is there any formula like that?
How have you done this. Is there any formula like that?
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