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HSSC JE Electrical 2018 Questions With YouTube Explanation Part One

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Haryana Staff Selection Commission (HSSC) Junior Engineer(JE) Electrical 2018 Questions With YouTube Explanation & PDF Part One

 

Question-1.Long distance railways operate on

(1) 600 V dc.

(2) 25 kV single phase ac.

(3) 25 kV three phase ac.

(4) 15 kV three phase ac.

Answer-2

Explanation-Railway electrification systems using alternating current (AC) at 25 kilovolts (kV) are used worldwide, especially for high-speed rail and long distance.

Question-2.The speed-time curve for urban service has no

(1) coasting period

(2) free running period

(3) breaking period

(4) acceleration period

Answer-2

Explanation-Urban Service or City Service
• In this service the distance between the stops is comparatively very short. (say 1 km or so)
• Time required for this run is very small.
• The acceleration as well as retardation is required to be high so that high average speed and short time run is obtained.
• Free run is not possible.
• Coasting period is also small.

SpeedTime curve for Urban Service

Question-3.The normal value of co-efficient of adhesion is

(1) 0.25

(2) 0.30

(3) 0.50

(4) 0.65

Answer-3

Explanation-

Coefficient of Adhesion in Traction (μa)=Maximum tractive effort that can be applied without slipping of wheels/Weight on driving excel

Normal value of co-efficient of adhesion is 0.25

Question-4.The voltage required to pass the necessary current through an electrolytic cell is of the order of

(1) 1-2 V

(2) 100-120 V

(3) 10-20 V

(4) 150-200 V

Answer-3

Explanation-The voltage required to pass the necessary current through an electrolytic cell is of the order of 10-20 V.

Question-5.What is the maximum load that is usually connected in a power sub-circuit

(1) 1000 W

(2) 2000 W

(3) 3000 W

(4) 4000 W

Answer-3

Explanation-Power sub-circuit-The load connected in a power sub-circuit normally should not exceed 3,000 watts and the number of outlasts connected on each sub circuit in no case should exceed two.

Single phase 15A sub-circuits (power sub-circuits) are used for connecting heaters, stoves, electric iron, small single phase motors etc.

Question-6.What type of starter will you recommend for a 20 kW squirrel cage induction motor

(1) Auto-transformer starter

(2) D-O-L starter

(3) Star-delta starter

(4) 3-point starter

Answer-1

Explanation-An Auto transformer Starter is suitable for a 20 kW squirrel cage induction motor.

Question-7.Compensating winding is used to

(1) Improve commutation

(2) Reduce armature reaction

(3) Reduce stray losses

(4) Improve look of machine.

Answer-2

Explanation-In order to neutralize the cross magnetizing effect of armature reaction, a compensating winding is used.

Question-8. _________ is cause of failure to build up voltage.

(1) No residual magnetism

(2) Actual field connections

(3) Less resistance

(4) High field current

Answer- 1

Explanation-Cause of failure to build up voltage in generator

  1. No residual magnetism of field
  2. Open field connection
  3. Field connection reversed
  4. Field circuit resistance too high

Question-9. __________ is done to improve efficiency and reliability of dc generator.

(1) Series operation

(2) Parallel operation

(3) Compound operation

(4) Load forecasting

Answer- 1

Explanation-Parallel operation is done to improve efficiency and reliability of dc generator.

Question-10.V curve is a graph of

(1) Armature voltage, Field current

(2) Field voltage, Field current

(3) Armature current, Field current

(4) Field voltage, Armature current

Answer-3

Explanation-V curve is a graph of Armature current and Field current.

Question-11.Thyristor is a __________ Layer and __________ Terminal semi-conductor device.

(1) 3, 3

(2) 3, 2

(3) 2, 2

(4) 4, 3

Answer- 4

Explanation-A thyristor is a solid-state semiconductor device with four layers of alternating P- and N-type materials.It have three terminal-Anode,Cathode,Gate

Question-12.Which among the below stated Boolean expressions do not obey De-Morgan’s theorem

(1) X’+Y’=X’.Y’

(2) X’.Y’=X’+Y’

(3) X.Y=(X+Y)’

(4) X’+Y=X.Y

Answer- 3

Explanation– According to De-Morgan’s theorem-The complement of the product of two or more variables is equal to the sum of the complements of the variables.

Question-14. Which of the following quantities are same in all parts of parallel circuit

(1) Resistance

(2) Voltage

(3) Power

(4) Current

Answer-2

Explanation-Voltage is the same across each component of the parallel circuit.

Question-14. Power factor is the ratio of

(1) Resistance to Inductance

(2) Inductance to Capacitance

(3) Resistance to Impedance

(4) Inductance to Impedance

Answer-3

Explanation-Power Factor=Cos(θ) = Real power (P)/Apparent power (S)= W/VA =R/Z

Question-15.The unit of resistivity is

(1) ohm-meter

(2) mho-meter

(3) ampere-meter

(4) voltage-meter

Answer-1

Explanation-Electrical resistivity is a fundamental property of a material that quantifies how strongly it resists the flow of electric current. A low resistivity indicates a material that readily allows the flow of electric current.The SI unit of electrical resistivity is the ohm⋅metre (Ω⋅m)

Question-16. The Load factor

(1) is always more than 1

(2) is always less than 1

(3) 1

(4) 0

Answer- 2

Explanation-The load factor is defined as the average load divided by the peak load in a specified time period,It is always less than 1

Question-17.. Nuclear power plant is normally used for

(1) Base load

(2) Peak load

(3) Average load

(4) Any load

Answer- 1

Explanation– The base load power plants typically are nuclear plants or coal-fueled,due to low-cost fuel and steady state power they can produce.

Question-18. From below which power station has maximum efficiency

(1) Steam Power Station

(2) Hydro-electrical Power Station

(3) Diesel Power Station

(4) Nuclear Power Station

Answer- 2

Explanation

Hydro Power station-85% efficient

Nuclear Power station-55% efficient

Diesel Power station-35% efficient

Steam Power station-25% efficient

Question-19.Which of the below metal is not used in Nuclear power plant as fuel

(1) Uranium

(2) Thorium

(3) Plutonium

(4) Magnesium

Answer- 4

Explanation-Metal is used in Nuclear power plant as fuel is enriched uranium (U-235) or reprocessed plutonium (Pu-239) and thorium.

Question-20.Which of the following power plant has practically no stand by loss

(1) Hydro-electric power plant

(2) Diesel power plant

(3) Nuclear power plant

(4) Steam power plant

Answer- 1

Explanation-Hydro Power station-85% efficient-This Plant has no stand-by losses

Question-21.What is the value of Load Factor

(1) <1

(2) >1

(3) >=1

(4) <0

Answer- 1

Explanation-The load factor is defined as the average load divided by the peak load in a specified time period,It is always less than 1

Question-22. In electric welding, arc blow can be avoided by

(1) using ac machines.

(2) increasing arc length.

(3) using bare electrodes.

(4) welding away from ground connection.

Answer- 1

Explanation-Arc blow is the undesirable effect of a electric welding during arc welding. They are two kinds of arc blow-Magnetic and Thermal.In electric welding, arc blow can be avoided by using ac machines.

Question-23.Which switch use in Staircase Wiring Circuits

(1) One way switch

(2) Two way center off switch

(3) Two way switch

(4) Double pole main switch

Answer-3

Explanation-Two way switching means having two or more switches in different locations to control one lamp. It use in Staircase Wiring Circuits

Question-24.Minimum size of the aluminium conductor in domestic wiring is

(1) 1.0 sq.mm.

(2) 2.5 sq.mm.

(3) 0.5 sq.mm.

(4) 1.5 sq.mm.

Answer-3

Explanation-Minimum size of the aluminium conductor in domestic wiring is 0.5 sq.mm.

Question-25.The material most commonly used for overhead line insulators is

(1) Rubber

(2) Wood

(3) Copper

(4) Porcelain

Answer-4

Explanation-Porcelain in most commonly used material for over head insulator.

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