Last modified: 31 May 2022 13:05
The course describes electromechanical system, in buildings and industries. First the basic circuit theory for AC and DC electricity are analysed. This helps the concepts of active and reactive power, and power factor to be understood. Thereafter, brief theory of electromagnetism is introduced .This is used to describe AC transformers and DC machines.
In the mechanical part , forced and free vibration with or without friction is described. This shows how the unbalanced rotational electrical motors and mechanical systems, can generate vibration and noise. Then it shows how the resonance phenomena could be avoided, and vibration is reduced .
The course is only available to students on the Graduate Apprenticeship in BEng in Civil Engineering
|Session||Second Sub Session||Credit Points||15 credits (7.5 ECTS credits)|
1. Introduction to phasors and AC circuit theory: test signals, RMS values and amplitude of sinusoids, phasor representation, single element circuits, introduction to phasor diagram
2. Multi-element circuits: two element circuits, development of procedure for AC series circuit analysis, concept of an impedance triangle, three element LCR circuit, concept of damping, application to simple sound filters
3. Resonance of three element AC circuits: mathematical representation of 3 element circuit, analysis of 3 element parallel circuit, definitions of conductance, admittance and susceptance, conditions for resonance, resonant frequency, half power bandwidth, voltage magnification factor, acceptor and rejector circuits, application of acceptor and rejector circuits .
4. Power factor correction of AC circuits: concept of the power factor, active and reactive components, concept of the power triangle, power factor improvement method, application of power factor improvement to power transmission problem, conditions for maximum power transmission (3 lectures Dr Thevar)
5. Basic Electromagnetism: concept of electromagnetism, B-H curves, extension to AC systems, sources of losses in electrical machines, right hand rule
6. Electrical machines: (a) ideal transformer and its equivalent circuit representation, ideal transformer under load, inclusion of magnetising current, iron losses, copper losses and leakage flux into equivalent circuit representation, primary and secondary side transformations, transformer tests
7. (b) basic electromechanics, shunt and separately excited DC generators, series and shunt DC motors, stepper motors, use of magnetising curves and operating points, torque and speed characteristics, the use of control resistors
8. Electromechanical Drives: Prime mover characteristics; load characteristics; steady state operating point; geared drives; speed control of dc motor drives.
9. Free vibration: Spring-mass-damper system from free body diagram to mathematical representation. Analogue of LCR circuit. Damping coefficient, logarithmic decrement. Practical examples: applications to car suspension system, damping in door closers and cannonballs .
10. Forced vibration: Spring-mass-damper system from free body diagram to mathematical representation. Analogue of LCR circuit. Frequency response. Dynamic magnifier. Vibration isolation Practical examples: car suspensions system, vibration amplitudes in rotating machines.
Information on contact teaching time is available from the course guide.
|Assessment Weeks||40,41,42||Feedback Weeks||43,44,45|
Feedback will be provided to the entire class in a summary of cohort exam performance, and on an individualised basis to students on request.
|Assessment Weeks||32||Feedback Weeks||35|
Feedback will be provided on MyAberdeen as comments on a marked up lab report.
There are no assessments for this course.
|Assessment Weeks||48,49,50||Feedback Weeks||1,2,52|
Individualised feedback available to student on request.
|Knowledge Level||Thinking Skill||Outcome|
|Factual||Remember||ILO’s for this course are available in the course guide.|