Demonstrative Video
Electrical Machines - Introduction
Electrical Machines is a device that can convert either mechanical energy to electrical energy or electrical energy to mechanical energy
mechanical \(\rightarrow\) electrical energy \(\Rightarrow\) Generator
electrical \(\rightarrow\) mechanical energy \(\Rightarrow\) motor
Since EM can convert power in either direction it can be used either a generator or a motor
EM use magnetic field to perform power conversion
Transformers - Introduction
Transformer is an electrical device that is closely related to EM
It converts ac electrical energy at one voltage level to ac electrical energy at another voltage level
Transformers operate on the same principles as generators and motors, depending on the action of magnetic field to accomplish the change in voltage level
Machines & Daily Life
Electric devices are omnipresent in modern daily life
At home motors run refrigerators, freezers, vacuum cleaners, blenders, air conditioners, fans and many similar appliances
At workplace, motors provide the motive power for almost all tools
Generators supply power used by all these motors
Why electric motors and generators so common?
Electric power is clean and efficient energy source
It can be easily transmit over long distances and easy to control
Electric motor does not require constant ventilation and fuel the way that an internal-combustion engine does
Hence well-suited for environmental use
Heat or mechanical energy can be transmitted over long distances to the place where it is to be used and can be used cleanly in home, office or factory
Transformers aid this process by reducing the energy loss between the points of generation and use
Reference Text Books
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Contents Overview
Chapter-1: Magnetic Circuits
Chapter-2-3: DC Machines- Generators & Motors
Chapter-4-6: Transformers- \(1\phi\), Auto-TF, & \(3\phi\)
Chapter-7-8: Induction Motors - \(3\phi\) & \(1\phi\)
Chapter-9: Alternators
Chapter-10: Synchronous Motors
EM Laboratory: 10-Experiments
Chapter-1: MAGNETIC CIRCUITS
Magnetic Field and its Significance
Magnetic Circuits and its Analysis
Important Terms
Comparison - Magnetic & Electric Circuits
Ampere-turn Calculations
Series & parallel magnetic circuits
Leakage flux
Magnetization or B-H Curve
Magnetic Hysteresis loss
Electro magnetic Induction
Faraday’s Laws of EMI
Induced Emf and Direction
Statically & Dynamically Induced Emf
Self and Mutual Inductance
Coefficients of Coupling
Inductances in Series and Parallel
Energy stored in Magnetic field
AC Excitation in Magnetic circuits
Eddy Current Loss
Electro-mechanical energy conversion devices
Production of Torques
EMF induced in a rotating coil placed in magnetic field
Elementary concept of EM
Chapter-2: DC Generators
Main constructional features
Simple Loop Generator and Commutator
Armature Coils and Brushes
Armature Windings and types
EMF and Torque equation
Armature Reaction and Commutation
Types of DC Generators
Voltage Regulation of a DC Shunt Generator
Characteristics, Application, and Losses
Efficiency and its Condition
Chapter-3: DC Motors
Working principle and Production of Back EMF
Developed Torque
Types and Characteristics
Application and Selection
Starting and Starters
Speed Control techniques
Electric Braking
Losses and Power Flow
Efficiency and tests performed
Chapter-4: Single-Phase Transformers
Construction and Working Principle
Ideal and Practical Transformer
Equivalent Circuit
EMF equation
No-load and Loaded operation
Voltage Regulation
Losses and efficiency
Transformer Tests
Parallel operation
Chapter-5: Autotransformers
Autotransformer Vs Potential divider Operation
Saving of Copper in an Auto-TF
Advantages and disadvantages
Equivalent Circuit
Conversion of 2-winding TF to Auto-TF
Comparison of characteristics
Applications
Chapter-6: Three-Phase Transformers
Merits of 3-phase TF over \(3\times1\phi\) TFs
Construction
\(3\phi\) TF Connections and selection
Parallel operation and conditions
Tap-changers and types
Open delta or V-V Connection
Scott or T-T Connections
Chapter-7: Three-phase Induction Motors
Constructional Features
Production of Revolving field
Principle of operation
Slip and Rotor Quantities- frequency, speed, emf, impedance, current and pf
Equivalent Circuit
No load and Load operation
IM Vs TF
Losses, Power flow, and Efficiency
Torque developed and conditions
Tests on IM
Advantages, Disadvantages and Applications
Starting Methods and Speed Control techniques
Chapter-8: Single-phase Induction Motors
Nature of field produced
Torque produced
Equivalent circuit
Rotating Magnetic field from 2-phase supply
Methods to make \(1\phi\) IM self-starting
Chapter-9: Alternators
General aspects & Basic Principles of SM
Generator and Motor action
Production of Sinusoidal alternating emf
Relation between frequency, speed and number of poles
Advantage of rotating field over stationary field system
Construction of SM and Excitation Systems
Armature windings, types and Important terms
Generation of \(3\phi\) Emf and its equation
Production of revolving field
Armature reaction and its effects
Equivalent circuit
Voltage regulation and determination techniques
Power Developed by Synchronous Generators
Two-Reactance Concept for Salient Pole SM
Parallel Operation of Alternators
Chapter-10: Synchronous Motors
Working principle
Effect of load
Equivalent circuit, and phasor diagram
Relations: supply voltage \(V\) & excitation voltage \(E\)
Torques and Power Developed
Power Flow
Effect of change in excitation
V and Inverted-V Curves
Effect of change in load
Methods of starting
Characteristics applications, merits and demerits
Comparison between SM and IM