Engineering Answers

Task 1:

Prepare and deliver a presentation on two applications using electrical energy chosen from the list below:

• intelligent street lighting systems,

• automated processes and robotics in manufacturing,

• automated rail transport systems,

• electric cars

• solar powered space travel

Your presentation should include an explanation (in terms of electrical or electronic principles) how they use two of the following:

• Electromagnetic effects

• Sensors (photodiode, LED, position detectors, Hall effect, etc.)

• Computer control (including PLA (programmable logic arrays)

• Battery technologies

Task 2

Explain and justify how the existing technology can be used to improve one of the systems you chose for Task 1. Specify in terms of electrical principles, how you suggested improvement work.

Make a detailed explanation of why a range of voltages is used such as 15 to 25kV at the generators and up to 400kV for transmission, and the reasons for other voltages (e.g. 33kV and 11kV down to 400/230 volts) for light industrial and domestic end users.

A: With the aid of a suitable diagram, describe the generation of electrical energy in a power station

B: With the aid of a suitable diagram, describe the transmission and distribution of electricitythrough to the end users

C: With the aid of a suitable diagram/sketch briefly describe the types of transformers used.Include double wound, autotransformers and isolating transformers

Magnetic materials properties: e.g. permeability, retentivity, coercivity, B-H curve, hysteresis and iron losses.

Soft magnetic materials: soft iron, silicon steel, mu-metal.

Hard magnetic materials: ferrites.

A. From the list of magnetic materials above select one soft magnetic material and one hard magnetic material. Sketch the B-H curves (hysteresis loops) of both selected materials. 

B. Give an example of where each one is used and state which of its properties makes it useful for the purpose.

Insulators properties: e.g. resistivity, breakdown voltage, operating temperatures, mechanical strength.

Solid insulating materials: plastics (e.g. PVC), butyl-rubber, glass, varnishes, paper.

Liquid and gas insulating materials: oil, air, sulphur hexafluoride gas.

A. From the list of insulators above select one solid and one liquid or gas. Describe it in terms of resistivity, maximum voltage capacity, operating temperature and mechanical strength.

B. Give an example of where each one is used and state which of its properties makes it useful for the purpose

Conductor’s properties: e.g. conductivity, resistivity, corrosion resistance, tensile strength and rigidity (hardness and toughness).

Solid conducting materials: e.g. copper, aluminium, steel, brass, carbon, soil (for earth continuity).

Liquid and gas conductors: e.g. electrolytes, conductive gases in fluorescent and discharge lighting.

A. Select one solid and one liquid or gas conductor from the list above. For each of them describe their properties in terms of: conductivity, resistivity, tensile strength and rigidity (where applicable). Then give an example of an electrical use for each of them.

B. State which of its properties makes them suitable for its electrical use.

With the aid of a suitable diagram describe the characteristics and principles of operation of a DC electromagnetic generator, give a real life example.

Note: You should include with your description a labelled diagram of the DC generator and describe the action of each major part.

• With the aid of a suitable diagram describe the characteristics and principles of operation of an AC electromagnetic generator, give a real life example.

Note: You should include with your description a labelled diagram of both the AC generator and its generated waveform and describe the action of each major part.

Task 4

A: Describe four renewable and four non-renewable energy sources, stating advantages and disadvantages of each system

B: Using the information from Task 4A above, justify the use of different energy sources, include a non-renewable source and renewable source, to provide a nation’s electricity supply. Use your own reasoning and/or other resources like, parliamentary reports, Greenpeace opinions, local opposition groups, national and global economics to support your justification.

The future of different methods and fuels, life span of equipment and actual fuels, cost of fuel production, hazards and environmental impact should be included.

1. An engine working on otto cycle has a volume of 0.5 m^3  pressure 1 bar and temperature 27C at the commencement of compression stroke.At the end of compression stoke,the pressure is 10 bar. Heat added during the constant volume process is 200 kJ.Determine
2. Percentage clearance
3. Air standard efficiency
4. Mean effectine pressure
5. Ideal power developed by the engine if the engine runs at 400 r.p.m.so that there are 200 cycles per minute.

The efficiency of an otto cycle is 50% and Y= 1.5 .What is the compression Ratio?