Essentially this module covers the Electrical and Electronic areas that are most likely to fall into the sphere of a mechanical engineer, and this is the basis on which the material was selected. The students are provided with a technical/economic overview of each field in order to enable them to supervise technical staff and to function effectively at managerial engineering level.
The electrical part is more advanced than the similar directly-applicable material taught after the theoretical material of the second year of this course. It focuses on similar equipment but from an operational point of view such as achieving more efficient starting and operation of motors by analysis using equivalent circuit models. Other aspects focus on a mechanical engineers electrical knowledge from a managerial point of view such as electricity tariff structures and how to reduce energy costs in a commercial enterprise. The pre-required theory was taught in the second year and only revisited for consolidation purposes as it becomes relevant in this year. However at the outset, the fundamental electrical circuitry on the second year syllabus is rapidly revised. This is principally for the benefit of the students who embark upon the course at the beginning of the third year.
The electronics part of the module focuses on instrumentation and associated signal processing. In particular, it reviews core concepts of instrumentation and metrology such as error, range and repeatability. A number of common transducers are investigated in detail as well as the typical analog and digital electronics employed for the signal processing.
- Revision of three-phase systems, star and delta connections: Mech. power = T ω, the efficiency of a three-phase motor: the volt-amps, the watts and the reactive power it takes from the supply: power-factor correction: the calculation of the cost of operating a motor given the costs of energy, demand and reactive energy, both before and after power-factor correction.
- The synchronous generator: The stator, rotor and AVR: synchronising: the equivalent-circuit: the phasor diagram on-load: the power-angle curve: the general load diagram: operating limits etc. The governor: no-load speed and speed-droop settings: operation of generators in parallel.
- The three-phase induction motor: the stator, synchronous speed: derivation of no = f/p: wound and squirrel-cage rotors: derivation of the equivalent-circuit: the torque/speed characteristic: losses and efficiency. The problems of high starting-current and low starting-torque.
- The three-phase variable-speed-drive for a low-slip induction motor: the block diagram: the dynamic torque/speed characteristic of the motor: the torque under static stator input and load: obtaining high starting torque.
- Electrical tariffs: importance to suppliers and the grid; breakdown of various tariffs and charges at domestic, commercial and industrial level: connection to the power grid: interpreting an energy bill; calculating an energy bill based on different tariffs and charges; calculating the wattless charge for commercial use; identifying ways to reduce commercial energy bill and calculating potential savings.
- Transducer and sensors; instrumentation performance terminology; potentiometer, encoder, LVDT/RVDT, ultrasonic sensor; strain gauge; resistance temperature detector, thermistor, thermocouple.
- Operational amplifier, inverting and non-inverting amplifier circuits.
- Micro-controllers and micro-processors; binary, decimal and hexadecimal numbering systems; digital and analog voltages; pulse width modulation; Arduino; analog-to-digital and digital-to-analog converters.
