Electrical Machine Dynamics
To enable students to gain an understanding of AC electrical machine dynamics and control and power transformers.
- Learning Outcomes
- 1.Apply transformer theory to three-phase power transformers.
2.Analyse fault currents in a power transformer and failure modes of power transformers and basic differential protection.
3.Evaluate the theory of machine dynamics to induction motor starting, speed control, braking, and protection.
4.Interpret the parameters used in the selection of motors.
5.Explain the operation of fractional horsepower motors.
6.Compare recent developments in machine design, control, and their application.
Three-phase transformer construction, application, principle of operation, performance, phasor diagrams, calculations using the equivalent circuit, vector grouping, vector grouping code symbols, NZ practice for interconnecting and paralleling, and harmonic reduction. Basic Differential and earth protection schemes, tap changers, power transformer sampling and diagnostic tools (gas and basic oil analysis), typical power transformer faults.
Starting methods for 3-phase induction motors. DOL, Star-delta, auto-transformer, primary resistance, electronic soft start, variable speed.
Motor speed control methods. Electro-mechanical methods, the effect of rotor resistance, electronic variable speed drives, and an introduction to vector drives.
Induction motor protection methods. Single phasing. Modern thermal, magnetic, thermistor, fuse, and thermal imaging protection methods.
Motor performance characteristics, variation of motor characteristics as a function of load, and motor selection. Calculations of mechanical output, starting time and
braking time using power, torque, and inertia equations. Calculations of torque and power over the speed range.
Factors that affect the dynamic performance of electrical machines.
Common fractional horsepower motors.
Latest developments in machine design and control are introduced.