- 2082 Bhadra · 2+2+2 marks
Types of hydropower plants by head, turbine, load
Short answer
By head: low (<15 m) Kaplan, medium (15-50 m) Francis, high (>50 m) Pelton. By turbine: impulse (Pelton) for high head low flow; reaction (Francis, Kaplan) for medium/low head. By load: base-load runs continuously, peaking runs only at peak hours often with storage, and pumped storage shifts energy from off-peak to peak.
Explain the different types of hydropower plants based on head, turbine characteristics and load characteristics.
Hydropower plants are classified in several ways. Three common ways are given below.
1. Based on head
| Type | Head | Typical turbine |
|---|---|---|
| Low head | below about 15 m | Kaplan, propeller, bulb |
| Medium head | 15-50 m | Francis, Kaplan |
| High head | above 50 m | Pelton, Francis |
Low-head plants use large flow and often a weir or barrage; high-head plants use small flow, long penstocks or tunnels. Some books use 30 m and 100 m as the limits.
2. Based on turbine characteristics
- Impulse turbine plants (Pelton, Turgo, cross-flow): The water jet strikes buckets at atmospheric pressure. Used for high head and low discharge. The runner is above tail water.
- Reaction turbine plants (Francis, Kaplan, propeller): Water flows through the runner under pressure and the runner is completely filled; they have a draft tube. Used for medium to low head and large discharge.
Specific speed increases from Pelton to Francis to Kaplan.
3. Based on load characteristics
- Base load plant: Runs continuously at high load factor. RoR plants and large thermal plants do this. They give firm energy.
- Peak load plant: Runs only for the peak hours (few hours a day). Has pondage or a reservoir; large installed capacity but low load factor. Examples: peaking RoR, storage and pumped storage.
- Intermediate (load following) plant: Follows the daily load change.
- Pumped storage plant: Takes energy off-peak to pump water up and generates in peak hours.
Selection depends on the head, discharge, system load shape and economy.
✓ Answer checked by Claude Opus 5.5 (high effort)
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