---
title: "Powerhouse layout with vertical axis Francis turbine"
subject: "Hydropower Engineering"
chapter: 8
key: "semester_7/hydropower_engineering:powerhouse-layout-vertical-axis-francis"
source: https://www.bctengineer.com/q/semester_7/hydropower_engineering/powerhouse-layout-vertical-axis-francis
site: BCT Engineering
---

# Powerhouse layout with vertical axis Francis turbine

Hydropower Engineering · Chapter 8: Powerhouse

- Asked in: 2081 Baishakh, 4 marks; 2076 Ashwin, 4 marks; 2070 Ashad, 4 marks (asked 3 times)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/hydropower_engineering/powerhouse-layout-vertical-axis-francis
- Whole chapter: https://www.bctengineer.com/md/semester_7/hydropower_engineering/chapter-8

## Question

Draw a section/general layout of a powerhouse using a vertical axis Francis turbine, showing the different parts of the powerhouse structure.

## Short answer

A vertical-axis Francis powerhouse has penstock and main inlet valve feeding the embedded spiral casing, guide vanes, runner, and draft tube below tailwater. The generator sits above on the same shaft, with thrust bearing, governor, overhead crane, and control room; substructure and superstructure complete the section.

## Answer

#### Section through a powerhouse with a vertical-axis Francis turbine

```text
      roof
   ============================
   ::::  Overhead crane  ::::     <- crane rail
   |                          |
   |        GENERATOR         |   generator floor
   |__________  |  __________|   (G.F.)
   |  exciter / thrust bearing|
   |     Turbine floor        |   (T.F.)
 --+---   shaft  |   --- Governor
   |      Guide vanes         |
   |  Spiral    ( Runner )    |
   |  casing                  |
   |           \  /           |
   |  Draft tube \/           |   draft tube
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tailwater
 foundation raft
 Penstock --> Main inlet valve --> Spiral casing
```

#### Parts shown
1. **Penstock and main inlet valve** (butterfly or spherical valve) at the entry to the spiral casing.
2. **Spiral (scroll) casing** embedded in concrete, supplying water around the guide vanes.
3. **Stay ring and guide vanes** controlling the flow, operated by servomotors from the governor.
4. **Runner** (Francis) mounted on the vertical shaft.
5. **Draft tube** under the runner discharging to the tailrace under tailwater.
6. **Turbine shaft, thrust and guide bearings.**
7. **Generator** (umbrella or suspended type) on the generator floor, with exciter above or below.
8. **Overhead travelling crane** on rails spanning the hall.
9. **Governor, oil pressure unit, cooling water, drainage and dewatering** in the galleries below.
10. **Superstructure** (roof, walls) and the control room beside the generator floor.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the correct path of water to the runner?
   A. Draft tube, runner, guide vanes
   B. Spiral casing, penstock, valve
   C. Penstock, main inlet valve, spiral casing, stay ring and guide vanes, runner
   D. Penstock, runner, spiral casing
   Answer: C. Water flows through the valve into the spiral casing and guide vanes before the runner. (Key point: Water path)

2. Where does the draft tube discharge?
   A. Into the spiral casing
   B. Into the generator floor
   C. Into the penstock
   D. Under tailwater into the tailrace
   Answer: D. It carries water from the runner to the tailrace below tailwater. (Key point: Draft tube)

3. What operates the guide vanes?
   A. Exciter
   B. Servomotors from the governor
   C. Overhead crane
   D. Draft tube
   Answer: B. The governor controls guide vanes through servomotors. (Key point: Guide vane control)

4. What is the role of the overhead travelling crane?
   A. It cools the generator
   B. It regulates the flow
   C. It spans the hall on rails to lift and erect heavy machine parts
   D. It generates power
   Answer: C. The crane on rail lifts heavy equipment such as the generator rotor. (Key point: Crane)

## Related in Hydropower Engineering

- [Powerhouse plan and sections (Francis, 10 MW)](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apowerhouse-plan-section-francis-10mw) — Hydropower Engineering, chapter 8
- [Powerhouse general arrangement and dimensions](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apowerhouse-arrangement-and-dimensions) — 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
- [Why vertical shaft arrangement is preferred](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Apowerhouse-vertical-shaft-turbine-generator) — Hydropower Engineering, chapter 8
- [Parts of pressurized and non-pressurized RoR intake](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aintake-parts-pressurized-nonpressurized-sketch) — Hydropower Engineering, chapter 5
- [Francis design (150 m, 25 m³/s)](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Afrancis-specific-speed-diameter-setting-150m-25cumec) — Hydropower Engineering, chapter 7, asked 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
- [Layout of a medium head Francis station](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Afrancis-medium-head-layout) — Power Plant Design, chapter 3, asked 2×
- [General parts of doors and windows](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Adoor-window-parts) — Building Technology, chapter 6, asked 2×
- [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