Hydro-electric Power Plant or Hydro-electric Power Station

Hydro-electric Power Plant or (Hydro-electric Power Station)

Hydro-electric Power Station:-

A generating station which utilizes the potential energy of water at a high level for the generation of

electrical energy is known as a hydroelectric power station.

Principle:-

➢A Dam is a barrier which stores water and creates water head. The type and arrangement

depends upon the topography of the site, foundation conditions, local materials and transportation available, occurrence of earthquake and other hazards.

➢ A spillway is used to protect the dam from the floods in the water level is beyond capacity of the

dam it is used as safety valve to the dam.

➢ A surge tank is used in medium and large head plants with closed conduit type penstocks. It is used to protect penstocks form water hammering effect.

➢ Surge Tank is also used to supply additional water in case of sudden load demands.

➢ Penstocks are open or closed conduit which carry water from reservoir to the turbines.

➢ Concrete penstocks are suitable for low heads (<30m) as greater pressure causes rapid

deterioration of concrete.

➢ The steel penstocks can be designed for any head the thickness of the penstock, increase with the

head or working pressure.

➢ The area of rainwater collected for storing of water in the dam is called catchment area.

➢ The amount of percentage of water which is converted into streams/river after evaporation

and filtration by land is called yield factor.

Types of Turbine:

(a) Based on Water Head (H) :-

Head	Turbine
< 15m	Kaplan (or) Movable Vane Propeller
15 to 70m	Kaplan (or) Francis
70 to 500 m	Francis (or) Pelton
> 500 m	Impulse (or) Pelton

(b) Based on Water in Penstocks:

Turbine	Water in Penstock
Pelton	8m/sec
Francis	4m/sec
Kaplan	2m/sec

(c) Based on speed (RPM):

Turbine	Speed (RPM)
Pelton	13 – 70
Francis	70 – 400
Kaplan	400 – 1000

Choice of site for Hydro-electric Power Station

1. Availability of Water

2. Storage of Water

3. Cost and type of land

4. Transportation Facilities

Advantages

(i) It requires no fuel as water is used for the generation of electrical energy.

(ii) It is quite neat and clean as no smoke or ash is produced.

(iii) It requires very small running charges because water is the source of energy which is available free of cost.

(iv) It is comparatively simple in construction and requires less maintenance.

(v) It does not require a long starting time like a steam power station. In fact, such plants can be put into service instantly.

(vi) It is robust and has a longer life.

(vii) Such plants serve many purposes. In addition to the generation of electrical energy, they also help in irrigation and controlling floods.

(viii) Although such plants require the attention of highly skilled persons at the time of construction, yet for operation, a few experienced persons may do the job well.

Disadvantages

(i) It involves high capital cost due to construction of dam.

(ii) There is uncertainty about the availability of huge amount of water due to dependence on

weather conditions.

(iii) Skilled and experienced hands are required to build the plant.

(iv) It requires high cost of transmission lines as the plant is located in hilly areas which are quite

away from the consumers