SSC JE 2014 Electrical question paper with solution(Morning-Shift)

SSC previous year solved electrical papers / March 25, 2022

Ques 91.  Consider a constant uniform magnetic field. A conductor moves across this field at a constant velocity. The emf induced in the conductor is termed as

  1. Self-Induced EMF
  2. Induced EMF
  3. Statically Induced EMF
  4. Dynamically Induced EMF✔

In dynamically induced emf the magnetic field system is kept stationary, and the conductor is moving, or the magnetic field system is moving, and the conductor is stationary thus by following either of the two processes the conductor cuts across the magnetic field, and the emf is induced in the coil. This phenomenon takes place in electric generators and back emf of motors and also in transformers.

 

Ques 92. A generating station supplies the following loads 15000 kW, 12000 kW, 8500 kW, 6000 kW and 450kW. The station has a maximum demand of 22000kW. Calculate the diversity factor

  1. 1.91✔
  2. 0.52
  3. 0.68
  4. 1.34

Diversity factor = Sum of individual maximum demand/Max demand of station

= (1500 + 1200 + 8500 + 6000 + 450)/22000

= 1.91

 

Ques 93. A magnetic circuit carries a flux Φi, in the iron part and a flux Φg in the air gap. Then leakage coefficient is

  1. Φi − Φg
  2. Φi/Φg✔
  3. Φg/Φi
  4. Φi x Φg

The ratio of total flux to the useful flux is called as the leakage coefficient in the magnetic circuit i.e Φi/Φg 

 

Ques 94. The maximum demand of a consumer is 2kW and his daily energy consumption is 20 units. Load factor is

  1. 21%
  2. 10.15%
  3. 41.6%✔
  4. 50%

Percent load factor = Average demand/Maximum demand

Average demand = daily consumption/24hr

= 20 x 100/24  (since 1 unit = 1 kwhr)

% load factor = (20 x 1000 x 100)/(24 x 2 x 1000)

= 41.6%

 

Ques 95. A wheat stone bridge has ratio arm of 1000Ω and 100Ω resistances, the standard resistance arm consists of 4-decade resistance boxes of 1000, 100, 10, 1Ω steps. The maximum and minimum value of unknown resistance that can be determined with this setup is

  1. 111100Ω, 10Ω
  2. 111100Ω, 1Ω
  3. 11110 Ω, 10Ω
  4. 10000 Ω, 10Ω

In a Wheatstone bridge, resistances of ratio arms are

R2 = 1000 Ω, R1 = 100 Ω

Unknown resistance = Rx

Standard resistance = Rs

Rx = R2 × Rs/R1

Given that standard resistance consists of 4 decade resistance boxes of 1000, 100, 10, 1Ω steps. Maximum value of Rs = 1000 + 100 + 10 + 1 = 1111 Ω

Minimum value of Rs = 1 Ω

Now, Maximum value of Rx = 1000× 100/1111 = 11110Ω

Minimum value of Rx = 100× 1/100 = 10Ω

 

Ques 96. Thevenin’s equivalent voltage and resistance between the terminal A and B for network of given figure is

numerical 96

  1. 2.5 V, 12.5Ω
  2. 2.5 V, 3.75Ω
  3. 12.5 V, 3.75Ω✔
  4. 12.5 V, 2.5 Ω

solution 96

 

Ques 97. Low-frequency operation of A.C series motor in traction application

  1. Improves its commutation but starting current increases
  2. Improves its commutation property but pf and η reduces
  3. Improves its commutation, pf and efficiency✔
  4. Adversely affects commutation but pf and η improves

AC series motors are used to produce the propulsion of the vehicle. This system uses AC voltages from 15-25KV at a frequency of 16.7 (i.e., 16 2/3) or 25 Hz. This low frequency leads to giving better performance and more efficient operation by the series motor.

The low-frequency operation of the overhead line reduces communication interferences. Also, the reactance of the line is low at the lower frequency and hence the voltage drop in the line is reduced. Thus increasing efficiency and P.f

 

Ques 98. The speed of a p-pole synchronous machine in rpm is given by

  1. 120 fp
  2. 120f/P✔
  3. 120P/f
  4. 120f/2p

The speed of p-pole synchronous machine is given as 120f/p

 

Ques 99. Which of the following motor has a high starting torque?

  1. Synchronous motor
  2. AC series motor
  3. DC series motor✔
  4. Induction motor

DC Series motor has high starting torque. We can not start the Induction motor and Synchronous motors on load, but cannot start the DC series motor without load because on very light load or no load as flux is very small (N ∝ 1/Φ), the motor tries to run at dangerously high speed which may damage the motor mechanically

 

Ques 100. What is the order of minimum displacement that can be measured with capacitive transducers?

  1. 10 m
  2. 1 cm
  3. 1mm
  4. 1 μm✔

The capacitive transducer is used for measuring the displacement, pressure and other physical quantities. It is a passive transducer which means it requires external power for operation. The capacitors measure both the static and dynamic changes. The capacitive transducer uses for the measurement of both the linear and angular displacement. It is extremely sensitive and used for the measurement of the very small distance of about 1 μm

 

For SSC JE 2017  Electrical paper with complete solution Click Here

For SSC JE 2015  Electrical paper with complete solution Click Here

For SSC JE 2014 (Evening shift)  Electrical paper with complete solution Click Here

For SSC JE 2013 Electrical paper with complete solution Click Here

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