Power system MCQ's (Multiple choise questions)

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1. The thermal efficiancy of steam power plant is?

A) 30%
B) 20%
C) 28%
D) 21%

ANSWER= (C) 28%
Explaination:- The thermal efficiancy of steam power plant is 28%.
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2. Rankine efficiancy of steam power plant is in the range of?

A) 35%-40%
B) 20%-25%
C) 5%-10%
D) 25%-30%

ANSWER= (A) 35%-40%
Explaination:- Rankine efficiancy of steam power plant is in the range of 35%-40%.
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3. The height of chimney in a steam power plant is Governed by?

A) quantity of flue gasses
B) the draught to be produced
C) pollution control
D) All of the above

ANSWER= (B) the draught to be produced
Explaination:- The height of chimney in a steam power plant is decided by the draught to be produced.
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4. The major heat losses in steam power plant is accurs at

A) penstock
B) condenser
C) evaporator
D) none of the above

ANSWER= (B)
Explaination:- The major heat losses in steam power plant is accurs in condesor.
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5. Economiser improve boiler efficiancy by?

A) 2-5%
B) 5-10%
C) 10-12%
D) None of the above

ANSWER= (B) 10-12%
Explaination:- Economiser improve boiler efficiancy by 10-12%.
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6. Pelton wheel turbine is used for minimum head up to?

A) 40m
B) 80m
C) 150m
D) 180m or above

ANSWER= (B) 180m or above
Explaination:- Pelton wheel turbine is used for minimum head up to 180m or above.
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7. In high head power plant the velocity of water in penstock is?

A) 2m/s
B) 4m/s
C) 7m/s
D) 15m/s

ANSWER= (A) 7m/s
Explaination:- In high head power plant the velocity of water in penstock is about 7m/s.
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8. The functin of surge tank is ?

A) To supply water at constant pressure
B) To relieve water hammer pressure in penstock
C) both of the above
D) none of the above

ANSWER= (B) To relieve water hammer pressure in penstock
Explaination:- The functin of surge tank in hydro power plant is To relieve water hammer pressure in penstock
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9. Water hammer is developed in a

A) penstock
B) surge tank
C) draft tube
D) altranator

ANSWER= (A) penstock
Explaination:- Water hammer is developed in a penstock.
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10. IN a hydropower plant the graphical repersentation of the discharge as function of time is known as ____

A) hydrograph
B) load duration curve
C) monograph
D) all of the above

ANSWER= (A) Hydrograph
Explaination:- A hydrograph is a graphical repersantation between discharge or flow of water with respect to time in hydropower plant.
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11.Boosters are basically ?

A) inductors
B) capacitiors
C) motors
D) Transformers

ANSWER= (D) Transformers
Explaination:- Booster transformers are used at the end of the power line to raised the voltage at desired value.
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12.photovoltaic cell converts ?

A) chemical energy into electrical energy
B) sun radiation into electrical energy
C) solor radiation into thermal energy
D) none of the above

ANSWER= (A) sun radiation into electrical energy
Explaination:- photovoltaic cell converts solor radiation into electrical energy by the process of photovoltaic effac.
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13.The size of the earth wire is based on the ?

A) maximum fault current carrying through the ground wire
B) rated current carrying capacity of service line
C) depend on the soil resistance
D) both A and C

ANSWER= (D) both A and C
Explaination:- The size of the earth wire is based on the both maximum fault current carrying through the ground wire and the soil resistance.
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14.Earth wire is made up of ?

A) Galvanized steel
B) iron
C) aluminium
D) copper

ANSWER= (A) Galvanized steel
Explaination:- Earth wire is made up of Galvanized steel.earth wire is used to protect from electric shock.
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15.when earth fault occurs:

A) voltage potencial at earth mat increase due to earthing
B) voltage potencial at earth mat decrease due to earthing
C) voltage potencial at earth mat remains zero
D) none of the above

ANSWER= (A) voltage potencial at earth mat increase due to earthing

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16.which of the circuit breaker take minimum time for installation?

A) Minimum oil circuit breaker
B) air blast
C) sulpher hexafluoride (SF6)
D) none

ANSWER= (C) sulpher hexafluoride (SF6)
Explaination:- sulpher hexafluoride (SF6) ‎will take minimum time for installation.
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17.the fault which are most commnly occur in underground cables are ?

A) Breakdown of cable insulation
B) short circuit fault
C) open circuit fault
D) all of the above

ANSWER= (D) all of the above

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18.By which of the following bus bar rated ?

A) current only
B) voltage only
C) current and voltage only
D) current,voltage,frequancy and short time current

ANSWER= (D) current,voltage,frequancy and short time current
Explaination:- bus bar is rated with the parameters current,voltage,frequancy and short time current.
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20.fusing factor of fuse is always ?

A) more than 1
B) less than 1
C) zero
D) infinite

ANSWER= (A) more than 1
Explaination:- the fusing factor is the ratio of minimum fusing current to the current rating of fuse and it is always more than one.
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