Applications of Induction Generators Motors and Transformers Generators

Applications of Induction Generators, Motors and Transformers

Generators �A generator is the opposite of a motor – it transforms mechanical energy into electrical energy. � Turbine generators are used in power plants �A turbine supplies the mechanical energy in the form of a rotating shaft � Turbines are machines that convert moving fluids (such as falling water or highpressure steam) into rotational motion

Turbine Generator �A turbine generator uses induction to produce electricity � A turbine turns a coil of wire inside a magnetic field � An alternating voltage/current is induced in the coil

AC: Alternating Current Generator Demo

Output of an AC Generator � The induce d voltage a output of an AC Generator is a Sinusoid maximum voltage = NAB b c d

Stator Stays Rotor Rotates Turbine Turns

‘Murica � Throughout North America (Canada, USA, Mexico) the same power specifications are used: � 110 -120 Volts AC � Frequency = 60 Hz

Motors � Motors energy � In convert electrical energy into mechanical some sense, motors are the opposite of generators � The applications of motors is endless: fans, blow-dryers, power tools, pumps, washing machines …

DC Motor � Motors use the motor principle (rotational force on a loop of wire in a magnetic field) � DC motors use direct current, so they can run on a battery �A DC motor requires a commutator (slip rings) which reverses the current in the armature � DC motors can be variable speed

Induction Motors � The induction motor is an AC motor that was invented by Nikola Tesla in 1883 � Induction motors have no brushes or slip rings � Their speed is determined by the AC frequency � Induction motors are cheap, quiet, and long lasting � Fans, fridge, dishwasher, washing machine, dryer

Transformers � Transformers are devices that increase or decrease the voltage of alternating current � Transformers make possible our high-voltage, high-efficiency power system � They can step down or step up the voltage

� Transformers work only if the current is changing; this is one reason why electricity is transmitted as ac.

�A transformer consists of two coils, either interwoven or linked by an iron core. � As the primary current oscillates, a changing magnetic field is created in the iron core which induces the secondary current primary current AC in iron ring secondary current load changing magnetic field AC out

� The ratio of the voltages (primary to secondary) is equal to the ratio of the number of turns (primary to secondary):

Example �If the primary coil has 75 turns, how many turns are needed in the secondary coil to step up the voltage from 120 V to 2400 V?

Solution �