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# INTRO ELECTRICAL MACHINES

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## Abu Ammar

on 17 January 2017

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#### Transcript of INTRO ELECTRICAL MACHINES

EDB3053
ELECTRICAL MACHINES

1. Introduction to
Machinery Principle

2. Transformer
3. AC Machines
4. DC Machines
Synchronous Generator
Induction Motor
DC Motor
DC Generator
Learning Outcome
Understand the
fundamental laws
in the
dynamic magnetic
systems and their relation to the electrical machines.

The Magnetic Field Principle
What is an Electrical Machine?
Equipment that is able to
convert
either
mechanical
energy to
electric
energy, or electric energy to mechanical energy.

The process is also known as

electromechanical energy conversion.

Power Concept
Magnetic field produces
when
current flow
in a wire
A
time changing magnetic field

induces voltage
in a coil of wire if it is passes through the coil.
Basis of transformer
“A
current-carrying wire
in the presence of
magnetic field
has
force induced
on it” (Basis of
motor
)

A
moving wire
in the presence of a
magnetic field
has a
voltage induced
in it” (Basis of
generator
)

Ampere’s Law

Electromagnetic Force
(Lorentz force)
Second Newton’s Law

In Electrical Machines
The Magnetic Field
Production of Magnetic Field
Magnetic Circuits
Example
Magnetic Behavior of Ferromagnetic Material
Energy Loss in a Ferromagnetic Material
Hysteresis Loss
Eddy Current Loss
Hysteresis Loss
Eddy Current Loss

INTRODUCTION TO MACHINERY PRINCIPLE
By:
Mohd Fakhizan Romlie, PhD
Email: fakhizan.romlie@petronas.com.my

Transformers
Voltage Regulation
2.Why Transformers are Important?
Make electricity generation possible at the most economic generator voltage level
Make electric power transmission take place at the most economic transmission voltage
Supply electric power to users at a safe and suitable voltage
Autotransformer
By:
Mohd Fakhizan Romlie, PhD
email: fakhizan.romlie@petronas.com.my
Learning Outcomes
1.What is a Power Transformer?
A device that changes AC electric power voltage level to AC electric power another voltage level at the same frequency through magnetic field action
Consist of two or more coils of wire wrapped around a common ferromagnetic core
Construction & How it works
Ideal Transformer
vs
Real Transformer
Ideal Transformer
Real Transformer
Per Unit System
Three Phase Transformer
How does a Transformer Work ?
Construction
The permeability of the core, approaches infinity
No core losses
No resistance in the windings
No leakage flux
Therefore:
Schematic Diagram
Example
Power

Impedance Transformation
Understand the purpose of a transformer in a power system
Know the voltage, current and impedance relationships across the windings of an ideal transformer
Understand how real transformers approximate the operation of an ideal transformer
Be able to explain how copper losses, leakage flux, hysteresis and eddy current are modeled in a transformer equivalent circuit
Use the transformer equivalent circuit to find the voltage and current transformations across a transformer
Be able to calculate the losses and efficiency
Be able to derive the equivalent circuit of a transformer from measurement
Understand per unit system
Be able to calculate voltage regulation
Understand auto transformer
Understand three phase transformers
Solution
LOSSES
ACCOUNTED
???
1. Copper Losses
2. Eddy Current Losses
4. Leakage Flux
3. Hysteresis Losses
EQUIVALENT CIRCUIT
OPEN CIRCUIT TEST
Referred to Primary Side
Referred to Secondary Side
Approximation - current excitation branch 2-3% only
Resistive heating losses in the primary and secondary winding of transformer. Proportional to square of current.
Resistive heating losses in the core of transformer. Proportional to square of voltage applied to transformer.
Associated with magnetic domains in the core. It is a function of voltage applied to the transformer.
Flux escape from the core and pass through only one side of the transformer. Its produce leakage inductance in the primary and secondary winding.
How?
1. Select 2 base quantities
- usually selected - voltage and power
2. Use electrical law
Example
Eliminates the need for voltage-level conversions and impedance transformation at every transformer.
Machine and transformer impedances fall within a fairly narrow range according to voltage and power ratings of the device.
Efficiency
EXAMPLE
Example
Voltage and Current Relationship
Apparent Power Rating
The Internal Impedance
Example
AC Machinery Fundamentals
Rotating Magnetic Field
Student should be able to explain using their own words - with proper diagrams
Definition
LO
Evaluate the fundamental operation of AC Machines
Voltage Regulation and Speed Regulation
AC Machines Power Flow and Losses
A Simple Loop in a Uniform Magnetic Field
By:
Mohd Fakhizan Romlie, PhD
email: fakhizan.romlie@petronas.com.my
Voltage Induced?
Forced Induced?
Detail explanation with equations related in section 3.1 of Chapman
Student should be able to explain the concept using their own words - with proper diagrams
Motor Power flow
Generator Power Flow
Generator - Voltage Regulation
Motor - Speed Regulation
The ability of a generator to keep a constant voltage at its terminals as load varies.

Ability of a motor to keep a constant shaft speed as load varies
Synchronous Generators
Speed
Construction and Operation Principle
LO
Analyze the performance characteristics of synchronous machines
How to Obtain Model Parameters?
Equivalent Circuit
Internal Generated Voltage
By:
Mohd Fakhizan Romlie, PhD
email: fakhizan.romlie@petronas.com.my
Source: http://articles.maritimepropulsion.com/author/Henderson.aspx?page=6
Phasor Diagram
Example
POWER AND TORQUE
Synchronous Generator Operating Alone
Induction Motor
Induction motor Construction
How it work?
LO
Torque
Torque Equation
Power Flow
Basic Concept
Analyze performance and characteristic of induction machine
Wound rotor
Squirrel Cage
Induction
Rotor Slip
Electrical Frequency
Example
Equivalent Circuit

Remember this
Transformer Model
Rotor Circuit Model
Final Equivalent Circuit
3hz
1710rpm
1800rpm
Maximum (Pullout Torque)
Torque-Speed Characteristic
Quiz
How we are going to do it?

1. 3 mins - individually - draw equivalent circuits and power flow diagram and think of how to do this example.

2. 5 mins - discuss with person next to your (in pair) - how to calculate all question. Don't calculate. Just write down how and write down formula to be used to calculate all question...

3. Discussion - I will randomly call anybody to come fw

4. Submit the quiz - at the end..

DC GENERATOR
FUNDAMENTALS AND CONSTRUCTION
Main Parts:
- stator
- rotor
-winding
-commutator
-brush
Internal Generated Voltage
Induced Torque

DC MOTOR
LO
Students should be able to :
- Describe the
equivalent circuit
for different types of DC motors
- Describe the
terminal characteristics
(torque vs. speed) for a DC motor
- Determine
speed and torque generated
by a DC motor given its terminal characteristics and magnetization curve

Separately Excited
Shunt Excited
Series Excited
Compounded
Permanent Magnet
Terminal Characteristic
Power Flow
Speed Control
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