DE5404                             ELECTRICAL MACHINES

Level 5                                             Credits 15                                            Version July 2010

LEARNING TIME

RECOMMENDED PRE-REQUISITE

DE4401 Electrical and Electronic Principles 1

DE5403 Electrical and Electronic Principles 2

RECOMMENDED CO-REQUISITE

Nil

AIM/PURPOSE

To develop understanding of the theory and application of single and three phase electrical machines

LEARNING OUTCOMES

On successful completion of this course, the student should be able to:

1.         Demonstrate knowledge of d.c. motor and generator operation

2.         Demonstrate knowledge of transformer theory.

3.         Demonstrate knowledge of and apply the theory of induction motors and synchronous machines.

4.         Describe the requirements and characteristics of selected motors and generators for a given application.

INDICATIVE CONTENT

●          Single loop conductor in a constant two-pole magnetic field as a motor; direction of rotation; factors influencing torque; shunt wound motor; series wound motor; cumulatively compounded motor; output calculations

●          Single loop conductor in a constant two-pole magnetic field, direction of rotation; the shunt generator; output calculations

●          Primary, secondary, turns ratio, kVA rating, equivalent circuit, operation on no-load and full-load, regulation, step up, step down, isolating, autotransformers

●          Magnetising current, core losses, copper loss, hysteresis losses, the narrow hysteresis loop, explanation of eddy current generation, and the purpose of laminations

●          Three-phase transformer configurations are explained

●          Electrical and mechanical power, torque, slip, efficiency, power factor; speed control using pole switching, slip ring motor, and variable frequency drives; testing, analysis and prediction of motor performance using transformer equivalent circuit model; induction machine as a generator (wind or hydro) running on the grid or stand alone

●          Induction motor starting and protection methods using traditional and solid state starters are described and compared

●          a.c. motors for given applications are selected and described.  Single-phase induction motors, split-phase, capacitor start, capacitor run, shaded pole and small synchronous; universal motor, stepper motor

●          Generator; operation on, and synchronisation with an infinite bus; motor starting methods, operating at variable power factors, as a synchronous capacitor start

●          Synchronous impedance, stability, and operational charts are explained

●          Calculations using the equivalent circuit of the three-phase synchronous machine

●          Motors or generators are selected for given applications and the selection justified in accordance with industry practice

●          Pumps, compressors, fans, high inertia loads, conveyors, winding machines, hydro generation, wind generation, thermal generation, gas turbine generation