UNIVERSITY OF TECHNOLOGY, JAMAICA

COLLEGE/ FACULTY: Faculty of Engineering and Computing

SCHOOL/ DEPARTMENT: School of Engineering

Final Examination, Semester 2

Module Name: ELECTRlCAL WORKSHOP

Module Code: ELEI003

Date: Date: April/May 2012

Theory/ Practical: Theory

Groups: ENG IE

Duration: TWO (2) HOURS

Instructions

i. ANSWER ANY THREE QUESTIONS.

ii. BEGIN EACH QUESTION ON A SEPARATE SHEET.

DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO

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Question 1 [25 marks]

(a) With the aid ofa schematic diagram, explain the operation of the three waycontrol of single light. [5 Mru-ks].

(b) Why is it necessary to perform a polarity, continuity and insulation test on a newinstallation? [5 Marks]

(c) With the aid of an example describe the process of performing a polarity test onan electrical installation branch circuit. [5 Mar-ks]

(d) Briefly discuss standard safely procedures that are to be followed during electricalinstallation. [10 Mar-ks]

Question 2 [25 marks]

(a) Determine the turns ratio and primary-to-secondary voltage ratio of a 4S0-

20SYI120V transformer. The transformer is delta connected on the high side and

wye connected on the low-voltage side. [5 Mar-ks]

(b) Explain the operation of the Single-Phase Induction Motor. [S Marks]

(c) The proposed load for a computer laboratory is shown in table I:

Table 1

Qty Specifications

3 110V,300 Watt

1 220V,15KW Air Conditioning Unit

Draw a detailed schematic of the installation and prepared a material list for the

installation, you may omit price. [15 Marks]

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Question 3 [25 marks]

(a) State two reasons for grounding in an electrical installation, [5 Marks]

(b) With the aid of a schematic or wiring diagram illustrate how grounding can beused to prevent unsafe conditions from occurring in electrical installations,

[10 Marks]

(c) With the aid of a schematic drawing explain the operation of a circuit that usestwo way switches to control a single lamp. [5 Marks]

(d) Explain the differences between an overload and a short circuit condition in acircuit. [5 Marks]

Total 75 marks

END OF PAPER

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