Quiz: Electrical Engineering
Exam: NPCIL
Topic: Miscellaneous
Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute
Q1. A 500 V sine wave generator appears across a 10 kΩ resistor. What is the instantaneous current in the resistor at a phase angle of 35°?
(a) 54.4 mA
(b) 92.3 mA
(c) 59 mA
(d) 40.6 mA
Q2. A 60 mH inductor carries a sinusoidal current of 20 A r.m.s. at a frequency of 48 Hz. The average power dissipated by the inductor is
(a) 0.67 W
(b) 0.81 W
(c) 0.46 W
(d) 0 W
Q3. What are the order and type of closed loop system for the plant transfer function G(s) = k/(s^2 (1+Ts)) and with unity feedback?
(a) Two and three
(b) Three and two
(c) Three and zero
(d) Two and zero
Q4. As type of system is increased
(a) no effect on stabilization
(b) stabilization becomes difficult
(c) stabilization becomes easy
(d) more errors are introduced
Q5. For controlling the vibration of the disc of ac energy meter, damping torque produced by
(a) Eddy current
(b) Magnetic effect
(c) Chemical effect
(d) Electrostatic effect
Q6. In substation which of the following device is a carrier communication device
(a) CVT
(b) Earth conductor
(c) Wave trap
(d) none of the above
Q7. When transmission voltage is increased, the line losses are
(a) decreased
(b) increased
(c) same
(d) none of the above
Q8. The feeder is designed mainly from the point of view of
(a) its current carrying capacity
(b) voltage drop in it
(c) operating voltage
(d) operating frequency
Q9. What should be the main characteristic of the null detector in a bridge measurement?
(a) accuracy
(b) precision
(c) Sensitivity
(d) Resolution
Q10. The dielectric loss of capacitor can be measured by which of the following?
(a) Wien bridge
(b) Owen bridge
(c) Shearing bridge
(d) Maxwell bridge
Solution
S1. Ans.(d)
Sol. V_m=√2×V_(r.m.s.)=√2×500 volts ;I_m=V_m/R=(√2×500)/(10×10^3 ) A
Now, i=I_m sinθ=(√2×500)/(10×10^3 ) sin35°=40.6×10^(-3) A=40.6 mA
S2. Ans.(d)
Sol. The average power dissipated by an inductor is zero.
S3. Ans. (d)
Sol. Two and zero
S4. Ans. (b)
Sol. stabilization becomes difficult
S5. Ans.(a)
Sol. Eddy current
S6. Ans.(c)
Sol. Wave Trap
S7. Ans.(a)
Sol. P = √3 VI cosϕ or
I=P/(√3 V cosϕ )
As transmission voltage V increases, the line current I and hence line losses are decreased
S8. Ans.(a)
Sol. A feeder is a conductor that connects the substation (or localized generator) to the area where power is to be distributed. Generally, no tapings are taken from the feeder. The feeder must carry the required current safely so that is designed form point of view of current carrying capacity.
S9. Ans. (d)
Sol. Resolution should be the main characteristic.
S10. Ans. (c)
Sol. Shearing bridge
