1) A balanced three phase system consists of _________.
a. Zero sequence currents only
b. Positive sequence currents only
c. Positive, negative and zero sequence currents
d. Only negative sequence currents
|
2) What is the value of the letter ‘a’ or ‘α’ which is commonly used in symmetrical components?
a. 1 ∠ 90°
b. 1 ∠ 30°
c. 1 ∠ 120°
d. 1 ∠ -120°
|
3) In what direction does the phasor get rotated if it is multiplied by the operator ‘a’?
a. Anti clockwise
b. Clockwise
c. Gets rotated by 90° in the clockwise direction
d. Gets rotated by 90° in the anticlockwise direction
|
4) What is the value of (1+ a + a2)?
a. 0
b. 1
c. -1
d. ∞
|
5) The positive sequence current is always equal to ______________.
a. Always zero
b. 1/3 of the negative sequence current
c. Negative sequence current
d. 3 times the negative sequence current
|
6) Which sequence component is represented by the following phasor?
a. Positive sequence
b. Zero sequence
c. Negative sequence
d. None of these
|
7) What is the value of the zero sequence current?
a. 3 times the current in the neutral wire
b. 1 / 3 times the current in the neutral wire
c. √3 times the current in the neutral wire
d. Equal to the current in the neutral wire
|
8) If the value of Ia = 100∠0° and Ib = 75∠-50° in a three phase three wire system, what will be the value of negative sequence current?
a. 23.12 ∠ -96.02 °
b. 59.12 ∠ -73.47 °
c. 76.21 ∠-84.25 °
d. 41.25 ∠ -36.85 °
|
9) What will be the value of IA , if Ia1 = 100 ∠ 30° and Ib2 = 20 ∠ 90°?
a. 111.35 ∠ 21.05 °
b. 99.12 ∠ 73.47 °
c. 135.24 ∠ 23.45 °
d. 63.85 ∠ 21.05 °
|
10) What will be the value of IC, if Ia1 = 100 ∠ 30° and Ib2 = 20 ∠ 90°?
a. 111.35 ∠ 21.05 °
b. 111.35 ∠ 15.05°
c. 111.35 ∠ 145.06°
d. 111.35 ∠ 158.94°
|
11) In the manufacture of transformers, ANSI prescribes certain standards. What is this standard?
a. High voltage side should lead the low voltage side by 30° with Y - Δ or Y - Δ connections.
b. High voltage side should lead the low voltage side by 60° with Y - Δ or Y - Δ connections.
c. High voltage side should lag the low voltage side by 30° with Y - Δ or Y - Δ connections.
d. High voltage side should lag the low voltage side by 60° with Y - Δ or Y - Δ connections.
|
Answer
Explanation
Related Ques
|
ANSWER: High voltage side should lead the low voltage side by 30° with Y - Δ or Y - Δ connections.
Explanation:
No explanation is available for this question!
|
|
12) For Y - Δ and Δ - Y transformers, the phase shift between the transformer windings is equal to “ n * 30° “. What does ‘n’ represent in the equation?
a. Number of windings
b. Number of turns
c. Turns ratio
d. Hour number
|
13) Phase shift of symmetrical components happens in which among the following?
a. Delta - delta
b. Star – delta
c. Delta – star
d. Both (b) and (c)
e. All of these
|
14) What is the value of the zero sequence impedance?
a. Z 0 = Z
b. Z 0 = Z + 2 Zn
c. Z 0 = Z + 3 Zn
d. Z 0 = 0
|
15) In the absence of neutral what will be the value of Z0 ?
a. 1
b. 0
c. Z
d. ∞
|
16) What is the value of negative sequence impedance?
a. 1
b. Z
c. Same as positive sequence
d. ∞
|
17) Zero sequence currents cannot flow in which of the following connections?
a. Delta
b. Star
c. Star – star
d. Both (b) and (c)
e. All of these
|
Answer
Explanation
|
ANSWER: Delta
Explanation:
No explanation is available for this question!
|
|
18) What happens to the zero sequence currents, if the neutral in the Y connection is absent?
a. Minimum
b. Zero
c. Maximum
d. ∞
|
19) What are the types of unsymmetrical faults?
a. Single line to ground fault
b. Double line to ground fault
c. Line to line fault
d. All of these
e. None of these
|
20) What percentage of faults occurring is single line to ground fault?
a. 50 %
b. 60 %
c. 35 %
d. 70 %
|
21) What are cross country faults?
a. A fault occurring at any point of the power system
b. Two or more faults occurring simultaneously on the power system
c. Line to line fault
d. All of these
e. None of these
|
Answer
Explanation
Related Ques
|
ANSWER: Two or more faults occurring simultaneously on the power system
Explanation:
No explanation is available for this question!
|
|
22) What are the terminal conditions in case of SLG fault, if the fault occurs in the phase A?
a. Vb = 0, Ia = 0, Ic = 0
b. Va = 0, Ib = 0, Ic = 0
c. Va = 0, Ia = 0, Ic = 0
d. Vb = 0, Ia = 0, Ib = 0
|
23) What is the value of fault current If , in case of SLG fault?
a. 3 * (Ea / Z1 + Z2 + Z0)
b. 2 * (Ea / Z1 + Z0)
c. 3 * (Ea / Z1 + Z2 )
d. 2 * (Ea / Z1 + Z2 + Z0)
|
24) Which among these is the connection diagram, in case of single line to ground fault?
a. Only a
b. Only b
c. Only c
d. Only d
e. None of these
|
25) What happens if the neutral is not grounded in case of the single line to ground fault?
a. Only the zero sequence impedance will be zero
b. The zero sequence impedance will be infinite
c. Fault current will be zero
d. Both (b) and (c)
e. All of these
|
26) What happens to the value of the fault current in case of SLG fault, if fault impedance is introduced?
a. The fault current increase
b. The fault current remains same as in case of SLG fault.
c. The fault current becomes zero
d. The fault current is reduced
|
27) What will be the sum of (IB + IY) in case of line to line fault, if the fault is occurring in the B and Y lines?
a. ∞
b. 0
c. 1
d. IR
|
28) Which among theses quantities are to be determined in slack bus?
a. P and Q
b. Q and |V|
c. |V| and δ
d. Q and δ
|
29) Which among the following buses constitute the maximum number in a power system?
a. Slack bus
b. P Q bus
c. P V bus
d. All of these
e. None of these
|
30) Which among the following is the main assumption to solve a load flow problem by GS method?
a. All the buses are to be considered as PQ bus including the slack bus.
b. All the buses are to be considered as PV bus including the slack bus.
c. All the buses are to be considered as PQ bus excluding the slack bus.
d. All the buses are to be considered as PV bus excluding the slack bus.
|
Answer
Explanation
Related Ques
|
ANSWER: All the buses are to be considered as PQ bus excluding the slack bus.
Explanation:
No explanation is available for this question!
|
|
31) What is the value of acceleration factor used in the GS method?
a. 2.3 – 2.7
b. 1.6 – 2.0
c. 1.2 – 1.5
d. 2.4 – 2.9
|
32) To control which among the following is the regulating transformer used in a power system?
a. Power flows
b. Frequency
c. Voltage
d. Power factor
|
33) Which types of equations are solved using Newton Raphson method?
a. Non linear differential equations
b. Linear differential equations
c. Non linear algebraic equations
d. Both (a) and (b)
e. All of these
|
34) What is the main drawback in NR method?
a. Slow to converge
b. A large memory allocation is required to store the jacobian matrix
c. The number of iterations is more
d. All of these
e. None of these
|
Answer
Explanation
Related Ques
|
ANSWER: A large memory allocation is required to store the jacobian matrix
Explanation:
No explanation is available for this question!
|
|
35) Which among the following matrix is sparse?
a. Jacobian matrix only
b. Y bus matrix only
c. Z bus matrix only
d. Both (a) and (b)
e. All of these
|
