--- title: "Powerhouse plan and sections (Francis, 10 MW)" subject: "Hydropower Engineering" chapter: 8 key: "semester_7/hydropower_engineering:powerhouse-plan-section-francis-10mw" source: https://www.bctengineer.com/q/semester_7/hydropower_engineering/powerhouse-plan-section-francis-10mw site: BCT Engineering --- # Powerhouse plan and sections (Francis, 10 MW) Hydropower Engineering · Chapter 8: Powerhouse - Asked in: 2073 Shrawan, 4 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/hydropower_engineering/powerhouse-plan-section-francis-10mw - Whole chapter: https://www.bctengineer.com/md/semester_7/hydropower_engineering/chapter-8 ## Question Draw plan and sections of a powerhouse showing various components. Assume a Francis turbine is used in this powerhouse to generate electricity of 10 MW. ## Short answer For 10 MW with two 5 MW units at 80 m head, flow is about 7.24 m3/s per unit, runner diameter about 1.06 m. The powerhouse plan has two units plus erection bay, length about 22 m, breadth about 11 m, height about 14 m; section shows penstock, valve, spiral casing, runner, draft tube, generator, crane and control room. ## Answer #### Assumptions Total 10 MW with 2 units of 5 MW each, net head 80 m, vertical-shaft Francis turbines, $\eta_o = 0.88$. $$ Q = \frac{5000}{0.88 \times 9.81 \times 80} = 7.24\ \text{m}^3/\text{s per unit} $$ Rated speed 500 rpm ($N_s \approx 148$) and runner diameter $D \approx 1.06$ m. #### Plan ```text <-------------- 22 m ---------------> +-----------------------------------+ ^ | Unit 1 Unit 2 Erection | | | (G) (G) bay | 11 m | MIV MIV (loading) | | +--||----------||-------------------+ v Penstock Control + switchgear room -> Draft tubes -> tailrace ``` #### Section A-A (through one unit) ```text roof truss ======================== crane rail --- EOT crane --- | GENERATOR | generator floor |__________ exciter ____________| | Turbine floor / governor | | Spiral casing ( runner ) | ~~|~~~~~~~~~~~ draft tube ~~~~~~~~~~~|~~ tailwater foundation raft penstock -> MIV -> spiral casing ``` #### Components shown - Penstock, main inlet valve, spiral casing, stay ring, guide vanes, runner and draft tube. - Generator, exciter and governor. - Overhead crane (about 30 t, lifting the rotor), erection bay and loading area. - Control room, switchgear, battery room, workshop and office; transformers outside. - Approximate dimensions: length about 22 m, breadth about 11 m, height about 14 m (draft tube floor to roof). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How is the 10 MW supplied in the assumed design? A. One 10 MW unit B. Two units of 5 MW each C. Four units of 2.5 MW each D. Five units of 2 MW each Answer: B. The answer assumes 2 units of 5 MW each with vertical-shaft Francis turbines. (Key point: Unit arrangement assumption) 2. How is the discharge per unit found? A. Q = P / (eta x 9.81 x H) = 5000/(0.88 x 9.81 x 80) = 7.24 m^3/s B. Q = P x H / 9.81 = 40.8 m^3/s C. Q = P / (9.81 x H) = 6.37 m^3/s D. Q = eta x P / H = 55 m^3/s Answer: A. Power P = eta x rho g Q H, so Q = 5000 kW/(0.88 x 9.81 x 80) = 7.24 m^3/s per unit. (Key point: Discharge formula) 3. Which is the correct order of the water path through a unit? A. Penstock, MIV, spiral casing, runner, draft tube B. Draft tube, runner, spiral casing, MIV, penstock C. Penstock, draft tube, runner, MIV D. Spiral casing, penstock, MIV, draft tube Answer: A. Water flows from the penstock through the main inlet valve into the spiral casing, over the runner, and out through the draft tube. (Key point: Components along the water path) 4. What approximate building dimensions are given? A. Length 22 m, breadth 11 m, height 14 m B. Length 11 m, breadth 22 m, height 5 m C. Length 50 m, breadth 30 m, height 30 m D. Length 14 m, breadth 14 m, height 22 m Answer: A. The answer gives length about 22 m, breadth about 11 m and height about 14 m from draft tube floor to roof. (Key point: Approximate dimensions) ## Related in Hydropower Engineering - [Powerhouse layout with vertical axis Francis turbine](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apowerhouse-layout-vertical-axis-francis) — Hydropower Engineering, chapter 8, asked 3× - [Francis runner design (40 m head, 10 m³/s)](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Afrancis-turbine-velocity-triangle-40m) — Hydropower Engineering, chapter 7 - [Powerhouse types; plan with three units](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apowerhouse-types-plan-three-units) — Hydropower Engineering, chapter 8 - [Powerhouse components by functional use](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apowerhouse-components-functional-use) — Hydropower Engineering, chapter 8 - [Francis overall efficiency with draft tube](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Afrancis-draft-tube-efficiency-32mw) — Hydropower Engineering, chapter 7 - [Study stages for 10 MW remote project](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Asmall-10mw-study-stages) — Hydropower Engineering, chapter 2 ## Related in other subjects - [Powerhouse layout with Francis turbine](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Apowerhouse-layout-francis) — Hydro Power, chapter 5 - [Why draft tube is used in Francis turbine](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Adraft-tube-francis) — Hydro Power, chapter 7 - [Auxiliary systems of a 100 MW Francis plant](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aauxiliary-ancillary-systems) — Power Plant Design, chapter 4 - [Bell's guide bund plan, sections, design steps](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Abells-bund-plan-design-steps) — Irrigation and Drainage Engineering, chapter 6