OPERATING PRINCIPLES OF MACHINES
- Transformer and rotating magnetic field in AC machines
- Induction Motor and Synchronous Generator
- DC Motor and DC Generator
A. Transformer
B. Rotating magnetic field
PRINCIPLES
PARTS
Core
Made up of ferromagnetic material
Coils
Three phase transformer
Single Phase Transformer
combinations of three single phase transformers but in different coil configuration
High voltage winding (connect in star configuration) 
Low voltage winding (connect in delta configuration)
Faraday's Law
A varying magnetic flux associated with the loop, induced an electromotive force (emf) across it.
FORMULAS
3.Es = es x Ns
1. ep=es
since magnetic flux passing through primary and secondary coil is the same
2. ep= Ep/Np
4. Es = (Ep/Np) Ns
5.Step up
6.Step down
Ns > Np
Es > Ep
Ns < Np
Es < Ep
To reduce energy loss (dissipate as heat)
FORMULAS
Speed of rotation of magnetic field = synchronous speed, ws
PRINCIPLES
Orientation of magnetic field changes with current, but its magnitude remains the same.
ws = (4πf) / P
unit= rad/sec
f=frequency of AC current P=number of poles
When P increases, ws will decreases
PARTS
Coils arranged 120 degrees apart
A. DC Generator (Mechanical energy to electrical energy)
B. DC Motor (Electrical energy to mechanical energy)
TYPES
PRINCIPLES
PARTS
PRINCIPLES
TYPES
PARTS
Armature
Commutator
Stator
Brushes
Rotor
Lorentz Law
Flemming's Left Hand Rule
Series Motor
Shunt Motor
Speed drop drastically
Good starting torque
Connected in series
Connected in parallel
Low starting torque
Constant speed
Armature core
Pole coils
Field magnet
Yoke
Commutator
armature windings
Brushes
Bearing
Lap winding
Wave winding
Shunt
Compound
Series
Faraday's Law (Moving wire)
Flemming's Left Hand Rules
A. Synchronous generator/ Alternator
(Mechanical energy to AC electrical energy)
B. Induction motor/ Asynchronous Motor
Two coils used arranged side by side
Bushing
Supply electrical energy
Ampere's Law
Determine the direction of varying magnetic flux
Right Hand Rule
Transformer immersed in cooling oil.
Conservator
Controls the volume of oil
Spreads out flux in air gap
Reduces reluctance
Act as a support
Produces magnectic flux when current passes through
Provides a path of a very low reluctance
FORMULAS
Lap Winding
No. of parallel path = No. of poles = No. of brushes
Wave windings
No. of parallel path = 2
Commutator
No. of segments = No. of armature coil
Facillitate the collection of currents
Convert AC current into unidirectional current
Collect current from commutator
Mechanical support for the poles
Protecting shield for generator
Made of : Cast iron, Cast/ Rolled steel
Made of: Pole core, Pole shoes
Provides a constant magnetic field
When currents flow through coil, emf is induced on it
Highly permeable steel layers
Enhance magnetic flux interaction
Help to maintain contact with the power source
FORMULAS
F= qV x B
I = (EMFin - EMFback) / R
EMF back directly proportional to Speed of motor
IMPORTANT PARTS
Armature coils
The place where electricity induced from magnetic field
Made by iron core : To enhance magnetic flux transfer
Rotor
Induces rotating magnetic field and AC current
Made by fixed steel lamina (reduce energy current losses due to eddy current)
Slip ring
Supply DC current to rotor from DC Generator
Auto voltage Regulator
Control current field
Increase the current field if thermal magnetic field is below desired limit.
PRINCIPLES
FORMULAS
Ampere's Law
Faraday's Law
Supply current from slip rings produce magnetic field
Induces current when there is varying magnetic field
Current magnitude is proportional to the rate change of magnetic flux
Strentgh of magnetic flux (depends on current produced)
PHENOMENON
consider: magnetic field (rotating), armature coil (stationary)
Magnetic field results in magnetic flux cutting the stationary armature coil
emf induced
currents start to flow in one direction for the first half and vice versa.
TYPES
Single phase
Triple phase
PRINCIPLES
Ampere's Law #
Faraday's Law #
IMPORTANT PARTS
PHENOMENON
FORMULAS #
Stator
Rotor
Supply given to the winding
magnetic flux generate coil due to presence of current
Flux from stator cut the coil in rotor
Rotor coil short circuited, current start flowing
Another flux will generate rotor
Rotor feel a torque and rotate through the direction of magnetic flux
Insulated iron core lamina
Prevent eddy current losses
aid electromagnetic induction
made of stacking thin slotted highly permeable steel laminations
Produces rotating magnetic field
Supply receiver