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Operating Principle of Machines (Transformer (benefits (Capable to…
Operating Principle of Machines
Rotating Magnetic Field in AC Machines
Synchronous speed= speed of rotator
ωs = 2πf=4πf/p
Actual motor has 2-14 poles
1Phenomena= Consists of 3 winding wire (carrying current) with 2 poles (North & South Poles) is arranged 120° apart.
Magnetic field varies as current varies
Uses the principle of rotating magnetic field
Each wire carrying current, produced single magnetic field
The higher the number of poles, the higher the synchronous speed achieved 1 rotation.
DC Generator
mechanical energy :arrow_right:electrical energy
Parts
yoke
Field magnet
poles coil
armature core
to rotate cutting magnetic flux of the field magnet
commutator
convert AC current to undirectional current
brushes
collect current
bearing
construction (armature winding)
lap winding
for high current, low voltage machines
eg: welding plants
wave winding
for high voltages, low current machines
eg: generator for lighting (Pasar Malam)
DC Motor
Parts
Stator
provide magnetic fields
armature (rotating part)
Enhance magnetic flux interaction
spring loaded commutator
mechanism
torque action= direction throughout the motion
coil perpendicular to B , so, torque action nears zero (irregular motion happen)
Add more loop to smoother the rotation of motor
Construction (rotor winding)
parallel connection (shunt motor)
low starting torque,but constant speed
series connection (series motor)
good starting torque,but speed drop drastically with load
electrical energy :arrow_right: mechanical energy
Synchronous Generator
Similar to DC generator work
principle
Work principle involves Faraday's law of
electromagnetic induction which says the current
is induced in the conductor inside a magnetic field
when there is a relative motion between that
conductor and the magnetic field.
Induction Motor
3-Phase Squirrel Caged Induction Motor
Working Principle of 3-Phased AC
current in the Stator winding creating a
Rotating Magnetic Field
Current is induced in the bars of
squirrel cage. And will start to
rotate
In short, electricity is inducted in the rotor by
electromagnetic induction. Insulated iron core
lamina is packed into the rotor to minimize loss of
eddy current.
Transformer
Better efficiency over long distances
Magnetic field is produced by coil and emf
Uses the principle of magnetic induction
Es/Ns=Ep/Np
Esls=Eplp
For three phase system, there are 3 phase wires and 2 neutral wire
Low voltage circuits connected in delta formation
High voltage circuits connected in star formation
Core is made of stacked steel lamination. Because less voltage loss
Energy loss is dissipated as heat
benefits
Capable to transfer power/ Electric energy for a long distance from power plant to houses/ factories.
Better transmission efficiency by avoiding power loss during transmission of power
