JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Prerequisites

Electrical Circuit Analysis-1 & Electrical Circuit Analysis-2 & Electrical Machines-I

Course Objectives:

• To deal with the detailed analysis of poly-phase induction motors & Alternators.
• To understand operation, construction and types of single-phase motors and their applications in household appliances and control systems.
• To introduce the concept of parallel operation of alternators.

Course Outcomes

After learning the contents of this paper the student must be able to

• Understand the concepts of rotating magnetic fields.
• Examine the operation of ac machines.
• Analyze performance characteristics of ac machines.

Course Objectives Program Outcomes

PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12 To deal with the 2 1 2 1 1 2 2 1 1 1 2 3 detailed analysis of poly-phase induction motors & Alternators To understand 2 1 2 1 1 2 2 1 2 1 2 3 operation, construction and types of single-phase motors and their applications in household appliances and control systems To introduce the 2 1 2 1 1 3 2 1 2 2 3 3 concept of parallel operation of alternators

Course Outcomes Program Outcomes

PO1 PO2 PO3 PO4 PO5 PO6 PO7 PO8 PO9 PO10 PO11 PO12 Understand the 2 1 1 2 1 1 1 1 1 1 1 3 concepts of rotating magnetic fields Examine the 2 1 1 2 2 1 1 1 1 1 2 3 operation of ac machines Analyse performance 2 1 2 1 3 3 3 1 1 1 3 3 characteristics of ac machines

UNIT - I

POLY-PHASE INDUCTION MACHINES: Constructional details of cage and wound rotor machines- production of a rotating magnetic field - principle of operation - rotor EMF and rotor frequency - rotor reactance, rotor current and Power factor at standstill and during operation. Rotor power input, rotor copper loss and mechanical power developed and their inter relation.

UNIT - II

CHARACTERISTICS OF INDUCTION MACHINES: Torque equation-expressions for maximum torque and starting torque - torque slip characteristic - equivalent circuit - phasor diagram - crawling and cogging, No-load Test and Blocked rotor test –Predetermination of performance-Methods of starting and starting current and Torque calculations, Applications. SPEED CONTROL METHODS: Change of voltage, change of frequency, voltage/frequency, injection of an EMF into rotor circuit (qualitative treatment only)-induction generator-principle of operation.

UNIT - III

SYNCHRONOUS MACHINES: Constructional Features of round rotor and salient pole machines – Armature windings – Integral slot and fractional slot windings; Distributed and concentrated windings – distribution, pitch and winding factors – E.M.F Equation. Harmonics in generated e.m.f. – suppression of harmonics – armature reaction - leakage reactance – synchronous reactance and impedance – experimental determination - phasor diagram – load characteristics. Regulation by synchronous impedance method, M.M.F. method, Z.P.F. method and A.S.A. methods – salient pole alternators – two reaction analysis – experimental determination of Xd and Xq (Slip test) Phasor diagrams – Regulation of salient pole alternators.

UNIT - IV

PARALLEL OPERATION OF SYNCHRONOUS MACHINES: Synchronizing alternators with infinite bus bars – synchronizing power torque – parallel operation and load sharing - Effect of change of excitation and mechanical power input. Analysis of short circuit current wave form – determination of sub-transient, transient and steady state reactance’s and Applications. SYNCHRONOUS MOTORS: Theory of operation – phasor diagram – Variation of current and power factor with excitation – synchronous condenser – Mathematical analysis for power developed. - Hunting and its suppression – Methods of starting – synchronous induction motor.

UNIT - V

SINGLE PHASE MACHINES: Single phase induction motor – Constructional Features-Double revolving field theory – split-phase motors – AC series motor- Universal Motor- -Shaded pole motor and Applications.

TEXT BOOKS:

• 1. P. S. Bimbhra, “Electrical Machinery”, Khanna Publishers, 2011.
• 2. I.J. Nagrath and D. P. Kothari, “Electric Machines”, McGraw Hill Education, 2010.

REFERENCE BOOKS:

• 1. Prithwiraj Purkait, Indrayudh Bandyopadhyay, “Electrical Machines”, Oxford, 2017.
• 2. M. G. Say, “Performance and design of AC machines”, CBS Publishers, 2002.
• 3. A. E. Fitzgerald and C. Kingsley, "Electric Machinery”, New York, McGraw Hill Education, 2013.
• 4. A. E. Clayton and N. N. Hancock, “Performance and design of DC machines”, CBS Publishers, 2004.