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

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

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

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

**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**

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

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

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

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

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

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

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

Nature of field produced

Torque produced

Equivalent circuit

Rotating Magnetic field from 2-phase supply

Methods to make \(1\phi\) IM self-starting

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

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