Electrical Machines (IITD)

The course introduces electrical machines - namely transformers, DC and AC rotating machines, which are, arguably, the most important components of energy and power conversion industry. Transformers, being static, are the easiest of electrical machines and hence they will be dealt with initially after introducing magnetic circuit fundamentals. DC and AC machines will be discussed after understanding the process of electromechanical energy conversion through a magnetic field. The efficiency, voltage regulation and characteristics of these machines will be discussed while they are functioning as generators. Further, their speed-torque characteristics, starting, braking, speed control and efficiency will be discussed while they function as motors. Every topic will include their applications in various power industries as well. INTENDED AUDIENCE: UG students and instructors PREREQUISITES: Basic Electrical Engineering, Circuit theory INDUSTRY SUPPORT: Machines manufacturing and drives manufacturing industries like Kirloskar, ABB and Siemens

COURSE LAYOUT

Week 1: Introduction to Electrical machines, Review of single-phase and three-phase circuits, complex notation, power and power factor Week 2: Magnetic circuits and flux calculations: MMF, Flux, permeability, reluctance, Ferromagnetic materials, BH loop, hysteresis, Eddy current losses Week 3: Assignment No 1 and 2 on AC circuits & Magnetic Circuits Week 4: Transformers: Principle of operation, ideal and practical transformer, efficiency and voltage regulation, Open circuit, short circuit and Load tests. Auto-transformer and instrument transformers. Parallel operation. Three-phase transformer fundamentals. Week 5: Assignment No. 3 and 4 on single-phase and three-phase transformers Week 6: Electromagnetic energy conversion principles: Filed energy, co-energy, Torque & power calculations, singly excited and doubly excited machines. Week 7: DC machines: Generators and motors; Construction, Different types of DC machines, principle of operation, torque and emf equation, Characteristics of DC generators and motors, Starting Braking and Speed control of DC Motors. Week 8: 3-phase induction machines: Construction, Different types of rotors, principle of operation, revolving magnetic field theory, Equivalent circuit, Torque expression,3 Torque-speed Characteristics of induction motors, Starting Braking and Speed control. Week 9: Single-phase induction motor: Types, Construction, Principle of operation, equivalent circuit, Torque-speed characteristics Week 10: Assignment No. 6 & 7 Problems on DC Generators and motors Week 11: Single-phase induction motor: Types, Construction, Principle of operation, equivalent circuit, Torque-speed characteristics Week 12: Three-phase Synchronous Machines: Construction, Different types, principle of operation, EMF equation, winding factor, OCC, SCC and calculation of synchronous reactance, Equivalent circuit, Voltage regulation and efficiency, Motoring operation, Power and Torque expressions, PF control, V and inverted V Characteristics of synchronous motors, Starting Braking and speed control.