The total power output in a hydroelectric installation depends upon A. the…
2023
The total power output in a hydroelectric installation depends upon
A. the total water flow
B. the electrical conductivity of water
C. atmospheric temperature
D. vertical distance through which water falls
Choose the correct answer from the options given below:
Answer: C. A and D only — ConceptFor a hydroelectric plant, the available hydraulic power is P = ρgQH, and the electrical output is P = ηρgQH. Here Q is volumetric water flow, H is…
- A.
A, B and C only
- B.
B and C only
- C.
A and D only
- D.
A, B and D only
Show answer & explanation
Correct answer: C
Concept
For a hydroelectric plant, the available hydraulic power is P = ρgQH, and the electrical output is P = ηρgQH. Here Q is volumetric water flow, H is hydraulic head, ρ is water density, g is gravitational acceleration, and η is turbine-generator efficiency. With the other quantities fixed, output varies directly with flow and head.
Application
Total water flow supplies Q: it measures the volume reaching the turbine per unit time.
The vertical distance through which water falls supplies H: it gives the gravitational energy available per unit weight of water.
Electrical conductivity and atmospheric temperature do not supply factors in the hydraulic-power relation: conductivity concerns charge transport in water, while atmospheric temperature describes the surrounding air.
Cross-check
The dimensions of ρgQH are (kg/m3)(m/s2)(m3/s)(m) = kg·m2/s3 = W. Therefore, the accepted combination is total water flow and vertical distance of fall only.