MCQs on Power Systems


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01․ Pumped storage plant is a
base load plant
peak load plant
both 1 and 2
none of the above

A base load power plant is a power station that usually provides a continuous supply of electricity throughout the year with some minimum power generation requirement. Base load power plants will only be turned off during periodic maintenance, upgrading, overhaul or service. Base load power plant has the character of slow demand respond, a mechanism to match generation with the load it supplies. Some examples of base load plants are 1. Thermal plants 2. Hydro plants 3. Nuclear plants 4. Tidal power plants A peaking power plant is a power station that only runs during high demands of electricity throughout the day during peak hours. Because of that, the price of electricity it generates is generally higher than the electricity generated by base load power plant, which operates continuously throughout the year. Some examples are 1. Pumped storage plant 2. Diesel plants 3. Hydro plants ( when water availability is less) 4. Gas fired power plants

02․ Advantages of pumped storage plants is/are
most economical as a peak load supply plant
used as load frequency control
operating time is minimum
all of the above

Advantages of pumped storage plants: 1. Most economical as a peak load supply plant 2. Used as load frequency control 3. If it is combined with thermal plant of an area load factor is increased 4. Pollution free 5. Easily adaptable for remote operation 6. Operating time is minimum

03․ Which of the following materials is/are used as moderators?
heavy water
graphite
beryllium
all of the above

Moderator is used to moderate the speed of neutron. Materials of moderator must have low molecular weight. In case of enriched uranium plants ordinary water is used as a moderator. In other plants heavy water, graphite, beryllium are used as moderators.

04․ In nuclear power plants which material is/are used as coolant?
liquid sodium
graphite
beryllium
all of the above

In a nuclear plant heat is produced due to nuclear fission change reaction and heat is absorbed by the coolant which is used to convert water into steam in the heat exchanger. This steam is used for producing electrical power output. The materials of coolant are water, heavy water, liquid sodium, sodium potassium etc.

05․ One million cubic meters of water is stored in a reservoir feeding a water turbine. The density of water is 993 kg/m³. If the centre of mass of water is 50 meters above the turbine and losses are negligible, the energy produced by that volume of water is
120 MWhr
140 MWhr
135.3 MWhr
130.2 MWhr

Power generation P = 9.81×10-3×ηQWH kW Where, η = Plant efficiency = 1 Q = Discharge of water = 1×106/3600 m³/s = 277.78 m³/s W = Density of water = 993 kg/m³ H = Mean head of water = 50 m Power generation P = 135.3 MW Energy E = P × t = 135.3 MWhr

06․ A coal fired steam power station working at a plant factor of 80% has one 500 MW generating unit. If the heat content of coal is 2 kWh/kg, the overall plant efficiency is 40% and a train load of coal is 2000 metric tons, then the number of trains required daily for the plant is
2
6
10
16

Maximum power Pmax = 500 MW Load factor = 0.8 Average power Pavg = 0.8×500 = 400 MW One day energy = 400×10³×24 kWhr = 9600×10³ kWhr Efficiency η = 0.4 Energy generated by coal = 2 kWhr/kg Therefore, actual energy generated by coal = 2×0.4 = 0.8 kWhr/kg One train coal = 2000×10³ kg One train coal can generate energy = 2000×10³×0.8 kWhr

07․ Which of the following plants is/are base load plants
nuclear
run off river
pump storage
both 1 and 2

Some examples of base load plants are 1. Thermal plants 2. Hydro plants 3. Nuclear plants 4. Tidal power plants 5. Run off river plants Some examples of peak load plants are 1. Pumped storage plant 2. Diesel plants 3. Hydro plants ( when water availability is less) 4. Gas fired power plants

08․ Which of the following statements is/are true?
The purpose of moderator is to slow down fast neutrons produced due to fission
The moderator material must have low molecular weight
both 1 and 2
nether 1 nor 2

Moderator: Moderator is used to moderate the speed of neutron. Materials of moderator must have low molecular weight. In case of enriched uranium plants ordinary water is used as a moderator. In other plants heavy water, graphite, beryllium are used as moderators

09․ A thermal generating station has an installed capacity of 15 MW and supplies a daily load of 10 MW for 12 hours and 5 MW for remaining 12 hours. The plant capacity factor for the station is
1
0.75
0.6
0.5

Plant capacity factor (Pcf) is defined as the ratio of average power to the plant capacity. Pcf = Average power/ Plant capacity Pcf = Energy produced by the plant/ (Energy that can be able to produce as per plant capacity during total hours)

10․ A thermal generating station has an installed capacity of 15 MW and supplies a daily load of 10 MW for 12 hours and 5 MW for remaining 12 hours. If the load factor is 0.8. Find the reserve capacity of the station?
5 MW
9 MW
10 MW
18 MW


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