Classification of Hydroplants - MCQs with answers

Classification of Hydroplants - MCQs with answers

Q1. The location of surge tank is close to ____________.

a. Tailrace
b. Dam
c. Turbine gate
d. Spillway

Explanation: The load on the generator keeps on fluctuating, when the governor opens the turbine gates suddenly to intake more water there is a tendency to create a vacuum in penstock. Its main function is to absorb these sudden changes in water requirements so as to prevent water hammer and vacuum. So it is desired to be placed near the power house i.e. turbine gates.

Q2. The limit of water head for the Francis turbines is_____________.

a. 200 m – 500 m
b. 30 m – 200 m
c. Less than 30 m
d. More than 500 m

ANSWER: b. 30 m – 200 m

Q3. The specific speed of a water turbine is_________.

a. Maximum speed i.e ((120*f) / P)
b. Minimum metric H.P
c. Unit H.P at all heads
d. Unit H.P under a unit head

Explanation: specific speed of a turbine is the speed of a scale model of turbine which develops a metric H.P under a head of one metre. The specific speed is given by, Ns = (N √Pt ) / H1.25 , where N is the speed of turbine in rpm, Pt is the power output in metric H.P, and H is the effective head in m.

Q4. The maximum limited head for a Kaplan turbine is___________.

a. 30 m
b. 50 m
c. 100 m
d. 75 m

Explanation: Propeller turbines are reaction turbine which is suitable for low head and large quantity of water. It is mainly suitable for heads below 30m.

Q5. The bulb turbines are mainly_________.

a. High speed turbines
b. High head and axial flow turbines
c. Low head and axial flow turbines
d. High pressure turbine

Explanation: The bulb turbine is an axial flow turbine; it is so called because water flows through the machine coaxial with the turbine shaft. It is specially designed for the low heads. These turbines are mainly suitable for the tidal plants. These turbines also have many advantages like it can be used for both very low and widely varying heads with a high efficiency due to the axial flow. They are easy and cheaper in construction.

Q6. Water hammer occurs in ______________.

a. Spillway
b. Penstock
c. Turbine casing
d. Surge tank

Explanation: sudden closure of turbine gates creates an increased pressure, which is called the water hammer occurring in the penstock. The water intake is limited with the help of water governor, which closes the turbine gate when the load is reduced. The surge tank helps in stabilising the velocity and the pressure in the penstock and reduces the water hammer and vacuum. The high pressure turbines are made from thick steel pipes.

Q7. The pumped storage power plant in India _________.

a. Does not exist
b. Bhakra Nangal (Punjab, Himachal Pradesh)
d. Koyna (Maharashtra)

Explanation: This type of plants have been introduced recently. There are only five plants with this scheme. The dams with this facility are :

1. Nagarjunasagar (AP) on Krishna river
2. Paithon (Maharashtra) on Godavari river
4. Panchet hill on Damodar river
5. Kadana (Gujarat) on mahi river

Q8. The hydroelectric power plants are__________.

a. Operating cost is high and initial cost is high
b. Operating cost is low and initial cost is high
c. Operating cost is low and initial cost is low
d. Operating cost is high and initial cost is low