Power Systems Questions and Answers

Answer: A

Uranium is used as the fuel in a nuclear power plant. The nuclear fission of uranium-235 in the reactor gives heat, which makes steam to run the turbine.

Natural uranium contains only about 0.7 per cent of the fissile isotope uranium-235, so the fuel is either used as natural uranium or enriched. A hydroelectric plant uses the energy of falling water, a diesel plant burns diesel oil, and a solar plant uses sunlight. None of them uses uranium. So the first option is correct.

Answer: C

The surge tank is the part of a hydroelectric power plant that overcomes the abnormal pressure in the conduit when the load on the turbine falls and acts as a reservoir when the load increases. When the gates close suddenly, the water hammer is absorbed by the rise of water in the tank, and when the load rises it supplies the extra water at once.

The penstock is the pipe that carries water to the turbine, the dam stores water, and the spillway passes the surplus water. So the third option is the answer.

Answer: D

The chimney is not a part of the coal handling and preparation system in a thermal power plant. It belongs to the draught and flue gas system, and it carries the gases away at a height.

A ball mill (to grind coal), a crusher (to break lumps) and a separator (to remove iron and sort the coal) are all parts of the handling and preparation system. So the fourth option is the answer.

Answer: C

The chimney produces a natural draught. The hot gases in the chimney are lighter than the cool outside air, so the difference in the weight of the two columns makes the gases rise through the chimney and draws air through the furnace, without a fan.

Induced and forced draught are made by fans, and a balanced draught uses both. So the third option is correct.

Answer: D

The reflector of a nuclear reactor is made of beryllium (graphite is also used). A reflector surrounds the core and sends back the neutrons that would escape, so that fewer neutrons are lost.

Boron is used to absorb neutrons in control rods, so it would remove neutrons and not reflect them. Cast iron and steel are structural materials and absorb neutrons. So the fourth option is the answer.

Answer: B

The plant capacity is 250 MW. The load factor is the ratio of the average load to the maximum demand, and the capacity factor is the ratio of the average load to the plant capacity. Dividing one by the other gives the ratio of the plant capacity to the maximum demand (MD), where C is the plant capacity.

\[ C = \frac{\text{LF}}{\text{CF}} \times \text{MD} \]

\[ = \frac{0.75}{0.60} \times 200 = 250\ \text{MW} \]

As a check, the average load is 0.75 x 200 = 150 MW, and 150/250 = 0.60, the capacity factor given. The other options do not give this. So the second option is correct.

Answer: D

The source of power is unlimited in a solar power plant. The sun's energy is renewable, and will be available for as long as the sun shines, so it is the inexhaustible source among the options.

Diesel, steam (which burns coal or other fuel) and nuclear plants use fuels that are limited in quantity: oil, coal and uranium. So the fourth option is correct.