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

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**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

â€¢ In this service the distance between the stops is comparatively very short. (say 1 km or so)

â€¢ Time required for this run is very small.

â€¢ The acceleration as well as retardation is required to be high so that high average speed and short time run is obtained.

â€¢ Free run is not possible.

â€¢ Coasting period is also small.

*S**peed*â€“*Time 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 (Î¼a)=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.**Â _________ 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

- No residual magnetism of field
- Open field connection
- Field connection reversed
- 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-Morganâ€™s theorem

(1) Xâ€™+Yâ€™=Xâ€™.Yâ€™

(2) Xâ€™.Yâ€™=Xâ€™+Yâ€™

(3) X.Y=(X+Y)â€™

(4) Xâ€™+Y=X.Y

**Answer-** 3

**Explanation**â€“ According to De-Morganâ€™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 sameÂ across each component ofÂ the parallel circuit.

**Question-14.**Â 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(Î¸) = 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 theÂ ohmâ‹…metreÂ (Î©â‹…m)

**Question-16.**Â 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**â€“ 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**â€“

HydroÂ Power station-85%Â efficient

NuclearÂ Power station-55%Â efficient

DieselÂ Power station-35%Â efficient

SteamÂ Power station-25%Â 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.**Â 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 blowÂ is the undesirableÂ effect of a electric welding duringÂ arc welding. They are two kinds ofÂ 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 switchingÂ means havingÂ twoÂ or moreÂ 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 inÂ most commonly used materialÂ for over headÂ insulator.