MCQs on Power Systems

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01․ Which of the following power planets is the least reliable

Wind energy is least reliable energy source by providing signification amounts of electricity. Wind power, as an alternative to fossil fuels is plentiful, renewable, widely distributed, clean, produces no green house gas during operation and use little land.

02․ A hydroelectric power station is commonly found in
hilly areas.
desert areas.

Hydroelectric power station are usually located in high hilly areas, where the dam can be easily built and large reservation can be obtained.

03․ The power output from an hydroelectric plants depend on
type of turbine, type of dam and type of catchment area.
type of dam, head, system efficiency.
type of dam, type of catchment area and discharge.
discharge, system efficiency.

The power developed by a hydro power plant depends upon the discharge and head and is directly proportional to their product and also proportional the system efficiency. The electrical power P is given as
P = WQHð × 9.81 × 10-3 KW.
Where W is specific weight of water in Kg/m3, Q is rate of flow of water in m3 / S, H is height of fall or head in meters and η is overall efficiency of operation.

04․ In hydroelectric power plants
both operating and initial cost are high.
both operating and initial cost are low.
operating cost is low and initial cost is high.
operating cost is high and initial cost is low.

As the large area required and construction cost is enormously high and takes a long time for erection, so initial cost is high for above reason. The operating cost is low because of fuel cost. The fuel of hydroelectric plant is water which is available of free of cost.

05․ Water hammer is developed in a
draft tube.
surge tank.

A reduction in load on the generator causes the governor to close the turbine gates and thus create an increased pressure in the penstock. This may result in water hammer phenomenon and may need pipe of extraordinary strength to withstand it otherwise the penstock may brust. So water hammer is developed in penstock.

06․ With reference to hydrometer station, the graphical representation of the discharge as function of time is known as
Load duration curve.

A hydro-graph is a graphical representation between discharge or flow with time in a hydro power plant.

07․ An hydro-graph indicates
the average run off during the period.
the discharge at any time during the period under consideration.
the maximum and minimum run off during the period.
all of the above.

An hydro-graph provides the following information 1. The discharge at any time during the period under consideration. 2. The average run off during of period. 3. The maximum and minimum run off during the period. 4. Total volume of discharge up to any time given by the area under the curve up to that time.

08․ A penstock is used as a condition between
the turbine and discharge drain.
the dam and the turbine in a hydro station.
the heat ex-changer and the turbine in nuclear power plant.
none of above.

Penstock is a closed conduit which connect the forebay or surge tank to the scroll case of turbine.

09․ In hydro power stations what is an enlarged body of water just above the intake and used as a regulating reservoir called
Fore bay.

The forebay server as a regulating reservoir storing water temporarily during light load period and providing the same for initial increase on account of increasing lad during which water in the canal is being accelerated. A forebay may be considered as an enlarged body of water just above the intake to store water temporarily to meet the hourly load.

10․ The function of a surge tank is to
produce surge in the pipeline.
relieve water hammer pressure in the penstock.
supply water at constant pressure.
none of above.

Surge tank is provided to absorb sudden changes in water requirements and reduce water hammer and negative pressure in penstock.