--- title: "High dam hydropower project components" subject: "Power Plant Design" chapter: 3 key: "semester_8/power_plant_design:high-dam-components" source: https://www.bctengineer.com/q/semester_8/power_plant_design/high-dam-components site: BCT Engineering --- # High dam hydropower project components Power Plant Design · Chapter 3: Hydro Power Plant Design - Asked in: 2081 Shrawan, 6 marks - Video: [How a Hydroelectric Power Plant Works? The Power of Water Explained – Turbines, Generators & Dams](https://www.youtube.com/watch?v=fjoOUjfzy-M) — WebMaxi ENG - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/power_plant_design/high-dam-components - Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-3 ## Question Discuss major components of a high dam type hydropower project with suitable schematic diagram. ## Short answer High dam project creates head and storage with a tall dam; major components: dam, reservoir, spillway, intake, bottom outlet, penstock, powerhouse at toe, tailrace, electrical works. Examples are Budhigandaki and Kulekhani; it gives firm power but has high cost and sedimentation problems. ## Answer A **high dam type** project uses a tall dam (usually above about 15 m, often 100 m or more) to create a large head and storage reservoir; the powerhouse is placed at the toe of the dam or at the end of a short waterway. ```text Reservoir ~~~~~~~~~~|\ ~~~~~~~~~~~~~~~~~~~~~| \ High dam Intake (trash rack)->|==\====\ | \ \ Penstock |____\ \ Spillway [Powerhouse] Turbine-Gen | | Tailrace Transformer | | River Switchyard ``` #### Major components 1. **High dam:** concrete gravity, arch or rockfill/earthfill; creates head and storage. It must be safe against overturning, sliding and seepage. 2. **Reservoir:** live storage between full supply level and minimum operating level; dead storage for sediment. 3. **Spillway and energy dissipator:** pass floods safely and protect the riverbed below. 4. **Intake:** at the dam face or in a tower, with trash rack and gates, placed above sediment level. 5. **Bottom outlet / sluice:** to flush sediment and empty the reservoir. 6. **Penstock:** short pressure pipe through or around the dam to the turbines (surge tank needed only if the waterway is long). 7. **Powerhouse:** at the dam toe; contains turbines (usually Francis), generators, governors and auxiliaries. 8. **Tailrace:** returns water to the river. 9. **Electrical works:** step-up transformer, switchyard and transmission line. Example: the proposed Budhigandaki (about 1200 MW) and Kulekhani reservoir in Nepal; worldwide, Three Gorges and Tehri. #### Advantages and limitations - Gives large head with a short waterway, firm power through the dry season, peaking capacity and flood control. - Needs very high investment and long construction time, causes submergence and resettlement, and loses storage to sedimentation, which is serious in Himalayan rivers. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Where is the powerhouse of a high dam project usually placed? A. Far downstream with a long canal B. At the toe of the dam or end of a short waterway C. At the top of the dam D. Inside the reservoir Answer: B. High dams give head directly, so the waterway is short and the powerhouse sits at the toe. (Key point: Powerhouse location) 2. What is the purpose of the bottom outlet or sluice? A. Admit design discharge to the turbine B. Absorb water hammer C. Flush sediment and empty the reservoir D. Return water to the river as tailrace Answer: C. Bottom outlets let sediment be flushed and the reservoir be drawn down. (Key point: Bottom outlet) 3. When is a surge tank needed in a high dam project? A. Always B. Never C. Only for Pelton turbines D. Only if the waterway is long Answer: D. The penstock is short, so surge protection is needed only with a long waterway. (Key point: Surge tank need) 4. Which must a high dam be safe against? A. Overturning, sliding and seepage B. Only evaporation C. Only sedimentation D. Only turbine vibration Answer: A. Stability against overturning, sliding and seepage is the basic design requirement. 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