Cork Institute of Technology
Bachelor of Engineering in Electrical Engineering - Award
(NFQ Level 7)
Summer 2007
Computer Applications
(Time: 3 Hours)
Answer THREE questions from Section A
and TWO questions from Section B.
For questions 1, 2, 3 and 4 use the computer.
For question 2 , use an answer book.
Use different answer books for each section.
Prof. E. McQuade
Mr. M. Hennessy
Mr. D. A. Collins
Dr. P. Fenton
Section A
1. (a) Figure 1(a) shows the hardware configuration of an industrial controller.
Using the software package PL7 Pro®, create a new application called “Calculate”
and configure the hardware as shown in the figure. [4]
(b) Figure 1(b) is a program for the controller referred to in (a), written in ladder language.
Using PL7 Pro® software, recreate the program in structured text language. [16]
2. (a) In a three phase system, the expressions for the instantaneous phase voltages are…
u1=100s in
ω
t
u2=100 sin
ω
t−2
π
3
u3=100 sin
ω
t−4
π
3
In an Excel® file called “Triphase.xls”, create a data table and chart showing the
variation of the phase voltages over one cycle of 360°. [8]
(b) Extend the data table in (a) to automatically calculate the rectified output voltage, being
at every instant the difference between the most positive and most negative phase
voltage. Add this voltage to the chart created in (a). [8]
(c) Identify the minimum and maximum values of the output voltage and the number of
output voltage pulses per cycle. Write these in your answer book. [4]
