# A 100 kVA. 415 V (line). star-connected synchronous machine generates rated open circuit voltage of 415 V at a field current of 15 A. The short circuit armature current at a field current of 10 A is equal to the rated armature current. The per unit saturated synchronous reactance is

1.  1.731

2.  1.5

3.  0.666

4.  0.577

4

1.731

Explanation :
No Explanation available for this question

# A three-phase, three-stack, variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is

1.  3°

2.  6°

3.  9°

4.  18°

4

Explanation :
No Explanation available for this question

# A single - phase 50 - kVA, 250V/500 V two winding transformer has an efficiency of 95 % at full load, unity power factor. If it is reconfigured as a 500 V/750 V autotransformer, its efficiency at its new rated load at unity power factor will be

1.  95.752 %

2.  97.851 %

3.  98.276 %

4.  99.241 %

4

98.276 \%

Explanation :
No Explanation available for this question

# A 230 V (phase), 50 Hz, three - phase, 4 - wire system has a phase sequence ABC. A unity power - factor load of 4 kW is connected between phase A and neutral N. It is desired to achieve zero neutral current through the use of a pure inductor and a pure capacitor in the other two phase. The value of inductor and capacitor is

1.  72.95 mH in phase C and 139.02 µF in phase B

2.  72.95 mH in phase B and 139.02 µF in phase C

3.  42.12 mH in phase C and 240.79 µF in phase B

4.  42.12 mH in phase C and 240.79 µF in phase B

4

72.95 mH in phase B and 139.02 µF in phase C

Explanation :
No Explanation available for this question

# The state equation for the current I1 shown in the network shown below in terms of the voltage Vx and the independent source V, is given by

1.  dI1/dt = -1.4Vx - 3.75I1 + (5/4)V

2.  dI1/dt = -1.4Vx - 3.75I1 - (5/4)V

3.  dI1/dt = -1.4Vx + 3.75I1 + (5/4)V

4.  dI1/dt = -1.4Vx + 3.75I1 - (5/4)V

4

dI1/dt = -1.4Vx - 3.75I1 + (5/4)V

Explanation :
No Explanation available for this question

# If u(t), r(t) denote the unit step and unit ramp functions respectively and u(t) * r(t) their convolution, then the function u(t + 1) * r(t - 2) is given by

1.  (1/2)(t - 1)(t - 2) (1/2)(t - 1)2(t - 2) (1/2)(t - 1)2 u(t - 1) none of these

2.  (1/2)(t - 1)2(t - 2)

3.  (1/2)(t - 1)2 u(t - 1)

4.  none of these

4

(1/2)(t - 1)2 u(t - 1)

Explanation :
No Explanation available for this question

# The integral  cos τdτ equals

1.  sin t cos t

2.  0

3.  (1/2) cos t

4.  (1/2) sin t

4

0

Explanation :
No Explanation available for this question

# X(z) = 1 - 3z -1, Y(z) = 1 + 2z-2 are Z- transforms of two signals x[n], y[n] respectively. A linear time invariant system has the impulse response h[n] defined by these two signals as h[n] = x[n - l] *y [n].where * denotes discrete time convolution. Then the output of the system for the input δ [n - 1]

1.  has Z - transform z-1 X (z) Y(z)

2.  equals δ [n - 2] - 3δ [n - 3] + 2δ [n - 4] - 6δ [n - 5]

3.  has Z - transform 1 - 3z -1 + 2z -2 - 6z -3

4.  does not satisfy any of the above three

4

equals δ [n - 2] - 3δ [n - 3] + 2δ [n - 4] - 6δ [n - 5]

Explanation :
No Explanation available for this question

# A loaded dice has following probability distribution of occurrences Dice value 1 2 3 4 5 6 Probability 1/4 1/8 1/8 1/8 1/8 1/4 If three identical dice as the above are thrown, the probability of occurrence of values 1, 5 and 6 on the three dice is

1.  same as that of occurrence of 3, 4, 5

2.  same as that of occurrence of 1, 2, 5

3.  1/128

4.  5/8

4

1/128

Explanation :
No Explanation available for this question

# Let x and y be two vectors in a 3 dimensional space and denote their dot product. Then the determinant det

1.  is zero when x and y are linearly independent

2.  is positive when x and y are linearly independent

3.  is non-zero for all non-zero x and y

4.  is zero only when either x or y is zero

4