G10 Electric Motors and Generators Flashcards
two ways on how electric current can be induced in a coil of wire
by moving a magnet into and out of a stationary coil of wire, or
by moving the coil of wire near a stationary magnet
a device capable of converting mechanical energy into electrical
energy. Understanding how voltage is induced in a loop of wire is essential in the
analysis of how it works.
generator
As the magnet is introduced, the magnetic field strength inside the coil increases
and the induced current in the coil moves in one direction.
Inducing Current by Moving a Magnet Through a Coil of Wire
As the magnet is pulled
out, the magnetic field strength falls and current is induced in the opposite
direction.
Inducing Current by Moving a Magnet Through a Coil of Wire
As the magnet is continuously pushed in and pulled out, the strength of the voltage
continues to change.
Inducing Current by Moving a Magnet Through a Coil of Wire
During this process, voltage alternately drops and rises,
creating an alternating voltage.
Inducing Current by Moving a Magnet Through a Coil of Wire
The more frequent the magnet is moved in and out
of the coil, the stronger the alternating voltage produced.
Inducing Current by Moving a Magnet Through a Coil of Wire
placing a stationary magnet near a rotating loop. It is easier to move the coil instead of moving the magnet. This is done by rotating a coil in a stationary magnetic field. This basic concept is the working principle behind electric generators.
As the loop rotates, it interacts with varying magnetic field lines, similar to what it would experience if a magnet is introduced and pulled out of it.
Fleming’s _-Hand Rule for Generators
Right
Thumb =
Fleming’s Right-Hand Rule for Generators
direction of force
Index finger =
Fleming’s Right-Hand Rule for Generators
direction of magnetic field
Middle finger =
Fleming’s Right-Hand Rule for Generators
direction of current
Mechanical energy exerted to rotate the coil generates electrical energy that can power a load such as a light bulb
Generator
current produced alternates back and forth
AC Generator
current produced is only in one direction
DC Generator
first person to create a generator in 1831 using electromagnetic induction
Michael Faraday
the generator he built is called the
Michael Faraday
Faraday disk
built one of the first dynamos - the first practical electric generators - in 1832
Hippolyte Pixii
the first practical electric generators - in 1832
dynamos
modern dynamos were independently developed by them
Sir Charles Wheatstone
modern dynamos were independently developed by them
Werner Von Siemens
modern dynamos were independently developed by them
Samuel Alfred Varley
invented the Ferranti- Thompson Alternator with the help of Lord Kelvin in 1882
Sebastian Ziani de Ferrant
alternating current generators
“Alternators
The production of a magnetic field by a current-carrying wire was first noted by _ _ _ in 1820 during one of his lectures.
Hans Christian Oersted
Oersted placed a compass near a wire connected to a battery. When the switch is turned on, the compass needle deflects as the current flows through the wire. This shows that electric current generates _ _.
magnetic field
One convenient rule in remembering the direction of magnetic field in a current carrying wire is the
Maxwell’s Right-Hand Grip Rule
right thumb=
Maxwell’s Right-Hand Grip Rule
direction of the current
direction of the curl of the remaining four fingers=
Maxwell’s Right-Hand Grip Rule
direction of the magnetic field
is a current-detecting device that uses a stationary magnet mounted with moving coil attached to a needle. The greater the current present in the wire, the larger the deflection of the needle.
galvanometer
The coil of the galvanometer rotates as current passes through it. A pointer attached to it also moves whenever the coil rotates. If there is no current flow, the coil and pointer are kept at zero position by a tiny spring.
converts electrical energy into mechanical energy
Electric Motor
current in an electric motor reverses direction each time the coil turns half-way
major difference between a galvanometer and a moto
used to identify the direction of movement of the current-carrying wire if placed in a magnetic field
Fleming’s Left-hand Rule for Motors
Thumb =
Fleming’s Left-hand Rule for Motors
direction of force
Index finger =
Fleming’s Left-hand Rule for Motors
direction of magnetic field
Middle finger =
Fleming’s Left-hand Rule for Motors
direction of current
The figure shows that the flow of the current is from the battery → conducting brush X → split ring P → arm AB → arm CD → conducting brush Y → split ring Q
The next figure shows the location of the parts of the electric motor after half rotation of the coil.
Notice that the location of arm AB and CD is reversed.
Also, the split ring Q now touches the brush X and the split ring P now touches the brush Y. This means that the flow of the current will be reversed after the half rotation.
The current flow will be from D → C → B → A. in effect, the reverse current flow will also reverse the force acting on the arms AB and CD
Therefore, the reversing of the current occurs every half rotation which creates a continuous rotating motion of an electric motor.
are powered by direct current sources like batteries.
In this type of motor, the coil of wire rotates while the magnetic field (produced by magnets or electromagnets) stays in one direction.
are commonly used in applications where motors need to be externally controlled
DC Motors
do not use brushes and commutators
Unlike a DC motor, an _ _ has a rotating magnetic field and a stationary armature
also has a longer lifespan and is usually utilized when there is a need for power at an extended period of time
AC Motors
invented the very first rotating device(motor) in 1822 known as Barlow’s Wheel
Peter Barlow
a freely rotating spiked wheel connected to a power source surrounded by a magnetic field from a horseshoe magnet
Barlow’s Wheel
some assume that he is the first one to invent a commutated rotary machine with magnets in 1828
Anyos Jedlik
He was able to build an oscillating electromagnetic motor in 1831 that he regarded as a “philosophical toy” - the first demonstration of continuous motion produced by magnetic attraction and repulsion
Joseph Henry
first demonstration of continuous motion produced by magnetic attraction and repulsion
philosophical toy
built the first “real” motor in 1834
Moritz Hermann Jacobi
the first motor to deliver a remarkable mechanical output power
Jacobi’s motor
invented the first practical motor in 1886
Frank Julian Sprague
a non-sparking motor that maintained relatively constant speed under variable loads
Frank Julian Sprague’s motor
developed a three-phase system in which instead of only a single magnetic field acting on a coil of wire is present, three rotating magnetic fields will act on coils of wire causing it to produce mechanical energy
Nikola Tesla
