Power Plant Terms

demand factor

The ratio of the maximum demand of a system, or part of the system, to the total connected load of a system or the part of the system under consideration.

surge tank

a device used to prevent water hammer in the turbine

pelton wheel turbine

a type of water turbine where a jet of water is made to fall on the blades or buckets and will move the turbine due to the impulse of water

reaction turbine

heads between 70 and 800 ft generally indicate this type of turbine

geothermal energy

heat energy naturally formed within the earth

blade power

is the actual power developed in the turbine

effective head

is the difference between the gross head and loss headworks

water power

is the maximum potential power output of a hydroelectric power plant, neglecting losses

rate of discharge

is the product of the velocity and cross-sectional area of water

mechanical efficiency

is the ratio of the brake power to the blade power

overall turbine efficiency

is the ratio of the turbine power output to the water power output

spiral casing

it conducts the water around the turbine

tailrace

it is a channel that conducts water away from the turbine

pumped storage plant

it is a hydroelectric plant in which excess water is pumped to an elevated space during off-peak period and the stored water will be used to drive hydraulic turbines during the peak period to meet the peak demand

fluid loop

primary purpose is to extract energy from the flow

spillway

provides an efficient and safe means of releasing flow water that exceeds the design capacity of the dam

load factor

ratio of average load to the peak load

use factor

ratio of the actual energy output, in the period of time considered, to the energy output which would have occured if the equipment had been operating at its full rating capacity during its service period

capacity factor

ratio of the actual energy produced to the maximum energy that might have been produced during the same period

operation factor

ratio of the duration of the actual service factor of a machine to the total duration of the period of time considered

utilization factor

ratio of the maximum demand of a system to the rated capacity of the system

gross head

the difference in elevation between headwater and the tailwater

draft tube

the functions of this hydraulic turbine part are: (1) enable the turbine to be set above the tailwater level without losing any head and (2) reduces the head loss at submerged discharge to increase the net head available to the turbine runner

penstock

the intake pipe to a hydraulic turbine from a dam

run-of-river plant

the power output of this plant depends on the water flow in the river; at low river flows the output decreases accordingly

penstock efficiency

the ratio of the effective head to the gross head

hydraulic efficiency

the ratio of the head utilized head to the effective head

runner

the rotating part of the turbine where the water imparts its energy onto the turbine shaft

specific speed

the speed of a hypothetical model turbine having the same configuration as the actual turbine, when the model would be of the proper size to develop 1 hp at at head of 1 ft

connected load

the sum of the continuous ratings of the load consuming apparatus connected to the system under consideration

headwater

the term used that refers to the water in the reservoir

wicket gate

these are movable vertical vanes that are actuated by the governor to control the flow of water and therefore the energy supplied to the runner

trash rack

this is a grid or screen composed of parallel bars to catch floating debris. It prevents, leaves, branches, and other water contaminants from entering the pennstock

kaplan turbine

this is a propeller-type reaction turbine with both adjustable guide vanes and runner blades