UPRVUNL-JE’21 EE: Daily Practices Quiz 20-Oct-2021

Table of Contents

UPRVUNL-JE’21 EE: Daily Practices Quiz

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

Q1. Guy wire is employed for
(a) Providing emergency earth route
(b) Supporting the pole
(c) Providing protection against surges
(d) All of the above

Q2. Synchronizing power of a synchronous machine is: –
(a) Inversely proportional to the synchronous reactance
(b) Equal to the synchronous reactance
(c) Directly proportional to the synchronous reactance
(d) Greater than the synchronous reactance

Q3. For increasing the range of voltmeter, connect a
(a) Low value resistance in series with voltmeter
(b) High value resistance in parallel with voltmeter
(c) High value resistance in series with voltmeter
(d) Low value resistance in parallel with voltmeter

Q4. Mho relay is used for protection in:
(a) Long transmission lines
(b) Short transmission lines
(c) Medium transmission lines
(d) Both long transmission lines and short transmission lines

Q5. If the equation of sinusoidal current is 141.4 sin 314t. Find the RMS value and frequency of the current.
(a) 400 A and 200 Hz
(b) 100 A and 50 Hz
(c) 300 A and 150 Hz
(d) 200 A and 100 Hz

Q6. The iron core in a transformer provides a ………………path to the main flux.
(a) Low reluctance
(b) High reluctance
(c) High conductivity
(d) Low resistance

SOLUTIONS

S1. Ans.(b)
Sol. A guy wire is designed to transfer some of the weight of the structures to the ground. It is used to support kinds of electric poles and towers in the power system, or hold up aerial masts for broadcasting and communications.

S2. Ans.(a)
Sol. Psyn=(VEf)/Xs cos⁡δ

S3. Ans.(c)
Sol. Voltmeter range increment: – High value resistance in series with it.
I.e.,Rs=Rm (m-1)
Rm = meter resistance
m=V/Vm≃I/Im

S4. Ans.(a)
Sol. Relay used for different configuration of transmission lines……
Short transmission line: reactance relay
Medium transmission line: impedance relay
Long transmission line: mho relay

S5. Ans.(b)
Sol. Irms=(Im )/√2=141.4/1.414=100 A
ω=2πf=314
f=314/(2×3.14)=50 HZ

S6. Ans.(a)
Sol. Iron core provides low reluctance path to the main flux.