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THESE QUESTION PAPERS HAVE BEEN OBTAINED WITH THE EXPRESS PERMISSION OF THE LECTURER TEACHING THE COURSE FOR ACADEMIC PURPOSES. ENUGU STATE UNIVERSITY OF SCIENCE AND TECHNOLOGY ESUT DEPARTMENT OF ELECTRICAL/ELECTRONICS ENGINEERING SECOND SEMESTER EXAMINATION 2011/2012 SESSION ELECTRICAL SERVICES DESIGN. (EEE 451) TIME: 1Hr 30Min (Answer All Questions) NB: IF you have not done any continuous assessment, write down what you have learnt in about 120 words first. Basic Concepts Where would you place a protective device in a circuit or an installation in Electrical Services Design? What is the sequence of control for power supply to an installation or building for effective power delivery, safety and adequate control? Explain this sequence of Electric Power Supply Control with the aid of an illustration. Where would you place a switch in an installation or circuit in Electrical services design and why? What is regulation in Electrical services design and why is it important? What regulations are appropriate for Control, Distribution and Excess-Current Protection? What is a Consumer Control Unit? What is the difference between Close and Coarse excess-current protection and explain each of them. What is Diversity? What is a spur? What is the difference between a ring circuit and a radial circuit? Give an example of each and explain how each circuit would be protected and why? With the aid of a diagram, show how you would supply electrical energy to an installation by carrying out a simple two wire installation. What is earthing? What is bonding? What is the difference between the two? What is Candela? What is Illumination? Explain the inverse square law as it applies to Illumination. Explain the Cosine law as it applies to Illumination? What is Luminous intensity? What is Luminous flux? What is Lumen? How would you calculate Illumination using the Lumen Method? What is maintenance factor? What is Coefficient of Utilization? What tests are carried out at the end of an installation to ensure that the design objectives are met and that the installation is safe (List and explain five of these tests.)? Application What is the procedure for the Electrical Services Design of an Installation? What is Load Analysis? What is Bill of Quantities and how is it produced? At what stage is a Certificate issued and why? Design a Simple installation for an Engineering Exhibition and Conference Center to be located at the Capital-City center for international engineering exhibitions and conferences. Produce a Bill of Quantities. Show the Schematic diagram for Protection and Control of the various circuits in your design. Explain your work. What is the relevance of earthing in this installation? With the aid of relevant diagrams, explain how this will be done. In your electrical Services Design, make provision for the various facilities required to make the center functional. What is a cable? List five different cables you are likely to recommend, specify and use in this design and explain why you made these specifications? How would you carry out an investigation to determine the voltage drop as a result of a cable installation in your design? What will be the guiding regulation for this purpose and how would you go about this investigation? Calculation A toy assembly shop is 12m long, 8m wide and 4m up to truses is to be illuminated to a level of 180lux. The Utilization and Maintenance factors are respectively 0.9 and 0.7. Make a scale drawing of the plan of the shop and set out the required lighting points, assuming the use of tungsten lamps and dispersive metallic reflectors. You may assume a lamp efficiency of 15lm/W, and spacing height ratio of unity. Consider the suitability of a Cable 1mm2 (1/1.13) which has a voltage drop per ampere per meter run of 40mV, and a current rating of 11A for an installation for a walk way 100 meters long lit by 230V, 100W lamps spaced 10 meters apart and controlled by one switch at the supply end. The wiring is single-core P.V.C. insulated cables enclosed in metal conduit. Determine the suitability of this installation and make your recommendations in your report based on your investigation and analysis. Explain your work.