PSPCL-JE’21 EE: Daily Practices Quiz 08-Oct-2021

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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 08-Oct-2021

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

Q1. Which of the following instruments has the same calibration in AC and DC?
(a) Moving iron type
(b) Moving coil type
(c) Induction type
(d) Electrodynamometer type

Q2. A slip test is conducted on synchronous generator to determine:
(a) Slip
(b) Direct and quadrature axis reactance
(c) Sub-transient reactance
(d) Positive and negative sequence reactance

Q3. Which of the following insulators is selected for HV application?
(a) Suspension type
(b) Strain type
(c) Disc type
(d) Pin type

Q4. In the salient pole of 3-phase synchronous machine the rotor will have
(a) Larger diameter, shorter axial length
(b) Smaller diameter, larger axial length
(c) Larger diameter, larger axial length
(d) Smaller diameter, shorter axial length

Q5. In a two-value capacitor motor, the capacitor used for running purposes is
(a) Air capacitor
(b) Paper spaced oil filled type
(c) Ceramic type
(d) A.c electrolyte type

Q6. A negative sequence relay is commonly used to protect
(a) An alternator
(b) A transformer
(c) A transmission-line
(d) A bus-bar

SOLUTIONS

S1. Ans.(d)
Sol. Electrodynamometer type instruments has the same calibration in AC and DC.
NOTE: A transfer instrument is one that may be calibrated with a d.c. source and then used without modification to measure a.c This requires the transfer type instrument to have the same accuracy for both a.c and d.c., which have electrodynamometer instruments have.

S2. Ans.(b)
Sol. A slip test is conducted on synchronous generator to determine Direct and quadrature axis reactance.
From slip test: X_d=V_max/I_min &X_q=V_min/I_max

S3. Ans.(a)
Sol. In higher voltage, beyond 33KV, it becomes uneconomical to use pin insulator because size, weight of the insulator become more. Handling and replacing bigger size single unit insulator are quite difficult task. For overcoming these difficulties, suspension insulator is used for HV application.

S4. Ans.(a)
Sol. 3-phase synchronous machine rotor construction:
• Salient pole rotor: larger diameter, shorter axial length
• Cylindrical pole rotor: smaller diameter, larger axial length

S5. Ans.(b)
Sol. Two-value capacitor motor also known as capacitor start capacitor run induction motor.
In a two-value capacitor motor:
At the starting, the two capacitors are connected in parallel.
Starting capacitor is short time rated and is almost electrolytic.
The run capacitor is long time rated and is made of oil filled paper.

S6. Ans.(a)
Sol. A negative sequence relay is commonly used to protect an alternator.
A relay which protects the electrical system from negative sequence component is called a negative sequence relay or unbalance phase relay.
The negative sequence relay protects the generator(alternator) and motor from the unbalanced load which mainly occurs because of the phase-to-phase faults.