Applied Electricity Paper 2 , Nov/Dec. 2011  
Questions:   1 2 3 4 5 6   Main
General Comments

Question 3

  1. State one difference between the voltages generated by a single-phase  and a three-phase synchronous generator.
    (b)      List four components of a high voltage overhead transmission system.
    (c)      State one advantage each of overhead and underground transmission




The expected answers were:

Single-phase synchronous generator

Three-phase synchronous generator



230 V – series connection

Between 400 V and 230 V

  •      Any four of the items listed below
  •  Steel towers
  •  Glass/porcelain insulators
  •  Aluminium conductors
  •  High voltage transformers



Overhead advantage

Underground advantage

Low investment costs
Less expensive maintenance

Long life expectancy
Reduced maintenance costs
Service uninterrupted by storms
Conserve valuable land
Reduced fire-fighting hazards
Prevention of accidents

The question was on Alternating Current Machines/Electrical Supply. It was unpopular with the candidates. The candidates that attempted the part (a) could not state the difference in the voltages generated by the two systems. They were not at home with the components of an overhead transmission system but rather stated overhead distribution system components.



Powered by Sidmach Technologies(Nigeria) Limited .
Copyright © 2015 The West African Examinations Council. All rights reserved.