PSPCL-JE’21 EE: Daily Practices Quiz 18-Oct-2021

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 18-Oct-2021

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

Q1. The current transformers used in differential protection of a star/delta transformer will be connected in the configuration of:
(a) Delta connection on both sides of transformer
(b) Star connection on both sides of transformer
(c) Star connection on star side and Delta connection on delta side of transformer
(d) Delta connection on star side and star connection on delta side of transformer

Q2. While conducting short-circuit test on a transformer the following side is short-circuited _________________:
(a) HV side
(b) LV side
(c) primary side
(d) None of these

Q3. There are _______ slip rings in a squirrel cage induction motor.
(a) 0
(b) 1
(c) 2
(d) 3

Q4. A current I = (10 +10 sin t) ampere is passed through moving iron type ammeter. Its reading will be
(a) zero
(b) 10A
(c) √150 A
(d) √2 A

Q5. Which type of winding is generally preferred for generating large currents on DC generators?
(a) Progressive wave winding
(b) Lap winding
(c) Retrogressive wave winding
(d) Current depends on design

Q6. The surge impedance of a 100 km long transmission line is 100 Ω. For a 50-km long transmission line the surge impedance is-
(a) 25Ω
(b) 50Ω
(c) 75Ω
(d) 100Ω

SOLUTIONS

S1. Ans.(d)
Sol. Differential protection of transformer:
Differential relay actually compares between primary current and secondary current of power transformer. If any unbalance then actuates and trip the CB.
If a transformer having (I_P/I_S) specifications then (I_P/1A) CT on primary and (I_S/1A) CT on secondary in such a manner that secondary current of both CT will oppose each other.
Buchholz relay is used for internal fault detection but differential protection scheme detects it in faster way.

S3. Ans.(a)
Sol. The rotor bars of squirrel cage induction motors are short circuited permanently. So, slip rings required=0.

S4. Ans.(c)
Sol. Given Current I = (10+10 sin t) A
Moving iron meter measure, the rms value.
(Irms=I0/√2)
∴ ireading=Irms=√(10^2+(10/√2)^2 )=√150 A
So, reading current will be √150 A.

S5. Ans.(b)
Sol. because in lap winding, parallel path is more so resistance will be less and current carrying capacity will be more.
LAP → Large current applications

S6. Ans.(d)
Sol. Surge impedance is independent of length of transmission line.

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