As explained ealier,alternating current is a current with alternating polarity.
It is used in insdustries for powering heavy duty motors and power cranes.They are cheap to generate and transmit than DC.
Generation Or Sources Of AC.
Alternating current can be generated from many source,but the most common are from motors and inverters.
1. AC from motors.
Pure AC can only be generated from motors.
Most of world's alternating electricity is generated from the conversion of mechanical power to electricity.
When coils of insulated coppers wire is wound on a soft iron core,and them made to spin in a magnetic field, electricity is induced into it as the magnetic field knocks out electrons from the coil.
The induced voltage in the coil then flows as electromotive force which can be used to power bulbs or loads.
The type of current generated depends on the type of motor used,
to generate AC we use an AC motor.
The difference between an AC and DC motor is the type of ring use to connect the rotary coil to external
circuit,and they are classified into two,namely slip ring for AC and split ring for DC.
The amount of voltage produced depends on the number of turns on the coil,the magnetic field strength and the speed of rotation.
The rotary energy is usually supplied by many force which includes; air Force,water pressure,gas and steam.
90% of the world's AC is generated from AC motor.There are three popular methods of generating AC from motors;
a.Hydro-electricity.
Current is generated from water made to drive an AC motor also Known as dynamo.
Dam is built with concrete and stones across a big river as shown above,the dam stops the the river flows and stores it.
A small hole is made at the wall and water gushes out with great force and made to drive a turbine as shown below.
The turbine moves with great speed and made to turn an AC motor.The out out current is then stepped up with transformers and transmitted at high voltage,at the consumer unit the high voltage is stepped down to about 110v to 220v.
The draw back is that it is very cost to build and maintain.
b.AC from wind turbine.
Here wind is made to drive a fan blade which in turn drives an AC motor.This type of energy source is renewable and cheaper to build than hydro electric,but the draw back is it only works in countries with regular wind or breeze.
c.Stream turbine.
Common heat energy source used to turn water to steam are:
1.coal.
2.wood
3.Gas
4.nuclear fusion.
No 1-3 are burned in air,and they produces heat exothermally,and inturn, turns water to steam.But the nuclear fussion works by producing enormous heat from radioactive materials by nuclear fusion.
c.AC from gasoline dynamo.
Electricity is generated by the rotary motion of a piston.
The generator piston works by ignition of compressed petrol and air with the release hot gas which pushes up and down the piston and inturn connected to a rotary shaft which drives an AC motor.It is an non-renewable source of power,it also pollutes the environment due to the emmision of carbon monoxide and other poisonous gas.
2.AC From Inverters.
This type of power source changes direct current from batteries into AC by means of transistors which switches on and off direct current repeatedly to produce AC.
The DC source are usually batteries,charged by solar cells or AC to DC converter by connecting to AC mains.
It is a renewable source of electricity and cheap to manufacture or maintain.
Tags:
Basic Electronics.
