PSPCL-JE’21 EE: Daily Practices Quiz 11-Oct-2021

Table of Contents

PSPCL RECRUITMENT 2021

Punjab State Power Corporation Ltd. (PSPCL), a power generating and distributing company of the Government of Punjab state, has released the notification for recruitment to the post of Clerk, Revenue Accountant, Junior Engineer (Electrical), Assistant Lineman & Assistant Sub Station Attendant Posts .
A total of 75 vacancies have been announced for the recruitment process of JE ELECTRICAL Engineering.

Exam Dates: 10 N0V-21 to 17 Nov-21

PSPCL-JE’21 EE: Daily Quiz

PSPCL-JE’21 EE: Daily Practices Quiz 11-Oct-2021

Each question carries 1 mark.
Negative marking: 1/4 mark
Total Questions: 06
Time: 06 min.

Q1. Which motor should not be used for centrifugal pumps?
(a) Series
(b) Shunt
(c) Cumulatively compound
(d) Differentially compound

Q2. DC series motors are very suitable for heavy duty applications such as electric railways, rolling mills because of
(a) Nearly constant speed
(b) Possibility of speed control
(c) High starting torque
(d) Low initial as well as maintenance cost

Q3. Which of the following loss in a transformer is zero at all operating conditions?
(a) Iron loss
(b) Eddy current loss
(c) Hysteresis loss
(d) Friction loss

Q4. A circuit is disconnected by isolators when:
(a) Line is on full load
(b) Line is energized
(c) There is no current in the line
(d) Circuit breaker is not open

Q5. A 3-phase, 6-pole, 50 Hz induction motor has a slip of 1 % at no load and 3 % at full load. The frequency of rotor current at standstill will be:
(a) 50 Hz
(b) 100 Hz
(c) 1.5 Hz
(d) Zero

Q6. Which of the following relation is correct for current carrying capacity of fuse element?
(a) I ∝ d
(b) I² ∝ d²
(c) I² ∝ d³
(d) I² ∝ d
Where d = diameter of fuse element

SOLUTIONS

S1. Ans.(a)
Sol. Series motors is best suited for electric traction work because of its large starting torque characteristics.

S2. Ans.(c)
Sol. Series motors is best suited for electric traction work because of its large starting torque characteristics. It is not suited for centrifugal pumps as in case of centrifugal pumps the starting torque is usually less than the running torque.

S3. Ans.(d)
Sol. Transformer is a static device.
Friction losses are involved with rotating parts of a machine. Since in a transformer all parts are stationary, friction losses will always be equal to zero, irrespective of the loading condition.

S4. Ans.(c)
Sol. Isolators operation occurs, when there is no current in the line.

S5. Ans.(a)
Sol. f_r=sf
At standstill condition: slip(s)=1
So, frequency of rotor current at standstill=supply frequency=50 Hz.

S6. Ans.(c)
Sol. Heat produced per sec = Heat lost per sec (convection, conduction, radiation)
⇒ I²R = K × d × l
⇒ I²(ρl/A) = K × d × l
⇒ (I^2∝d^3 ) also called fuse law.