Autumn 2008/09 Electrical Planning Exam for Electrical Engineering Students, Exams of Electrical Engineering

Download Autumn 2008/09 Electrical Planning Exam for Electrical Engineering Students and more Exams Electrical Engineering in PDF only on Docsity! CORK INSTITUTE OF TECHNOLOGY INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ Autumn Examinations 2008/09 Module Title: Electrical Planning Module Code: ELEC 6017 School: Electrical and Electronic Engineering Programme Title: Bachelor of Engineering in Electrical Engineering – Stage 2 Programme Code: EELEC_7_Y2 External Examiner(s): Mr. Gerard Beecher, Dr. Maeve Duffy Internal Examiner(s): Mr. Joe Buckley Instructions: Answer THREE questions. All questions carry equal marks. In marking scripts, the Examiner will take account of clarity of expression and communication skills. Duration: 2 Hours Sitting: Autumn 2009 Requirements for this examination: Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator. Q1. (a) Two lighting standards are mounted 50m apart. A single lantern with a light intensity of 5000 candelas is mounted at a height of 10m on each standard. Calculate the illuminance at a point between the two standards located 9 m from one standard and 41m from the other. (8 Marks) (b) What effect does room proportion have on the utilisation factor? (6 Marks) (c) Suggest some remedies for solving the problem of discomfort glare associated with an artificial lighting installation. (6 Marks) Q2. The electrical loading in a commercial premises is set out in the table below: Load P(KW) Power Factor Diversity g Fluorescent lighting 45 0.89 0.9 Life motors 16.5 0.85 0.67 Air conditioning motors 50 0.9 0.9 Direct heating 39 1 0.35 Socket outlets 72 0.95 0.18 (a) Using mathematical techniques, evaluate the total load for design purposes. The design load should include 25% spare capacity. (8 marks) (b) Using your result in (a) above, calculate the likely rating of the power transformer to be requested at the time of application for supply to the Utility Company (ESB). (6 marks) (c) Given that the transformer and user’s main switchgear will be in close proximity and that the standard impedance for the supply transformers is 5%, what current rating and breaking capacity should the user’s main circuit breaker have? You may assume that the customer is supplied from a three-phase 400V, 50Hz supply. (6 marks)