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Cork Institute of Technology
Bachelor of Engineering in Electrical Engineering — Award
(National Diploma in Engineering in Electrical Engineering — Award)
(NFQ — Level 7)
Autumn 2005
Computer Applications
(Time: 3 Hours)
Answer THREE questions from Section A and TWO questions from Section B. Use the computer where appropriate. Use different answer books for each section.
K. O'Connell Mr. M. Ahern Mr. D. A. Collins Mr. P. Fenton
Section A
- (a) Figure 1 (a) shows a number of graphical symbols encountered in power electronics. The symbols are set against a background grid of 2.5 mm. Draw the symbols to the appropriate scale in a new AutoCAD file called ‘Circuit.dwg’. [4]
(b) Create an attribute called ‘ID’ for each symbol to act as a reference designation during insertion. The default values are: thyristor –V1, capacitor –C1, inductor –L1 and resistor –R1. In each case, the attribute is to be placed to the left of the symbol and the text is to be middle-right aligned in 2.5 mm high ‘Arial’. [4]
(c) Create a W-Block for each symbol. Give each block an appropriate name and insertion point. Save the blocks in the same folder and disk as the drawing file. [8]
(d) Use the W-blocks to create the circuit diagram shown in Figure 1 (b). [4]
- (a) In an AC circuit, the instantaneous voltage and current are given by …
u = U max sin ω t and i = I max sin( ω t +π 4 )
where the peak voltage U max is 32.5 V, and the peak current I max is 25 A. In an Excel ®^ file called “Waveform.xls” create a table showing the instantaneous voltage, current and power in a full cycle. Use increments of 15º for this purpose. [9]
(b) Use the file to automatically chart the voltage, current and power over one cycle. The X–axis is to be titled “Angle [degree]”; it is to have a minimum value of 0, a maximum of 360 and major units of 30. The primary Y-axis applies to the voltage and current and is to be titled “Voltage [V] Current [A]”; it is to have a minimum value of -100, a maximum of 100 and major units of 20. The secondary Y-axis applies to the power and is to be titled “Power [W]”; it is to have a minimum value of -120, a maximum value of 880 and major units of 100. [6]
(c) Use an equation editor to write the given expressions for the voltage and current, and superimpose both on a blank portion of the chart. [5]
- (a) Figure 2 (a) shows the sequential function chart for an industrial control task; the
accompanying tables indicate the conditions for clearing the transitions and the actions attaching to the steps. Using the software package PL7 Pro®, create a new application called “Process” and configure the hardware as shown in Figure 2 (b). [5]
(b) Create the chart as shown in Figure 2 (a) and program the required transition conditions in ladder language. [10]
(c) Program the required actions for the process using ladder language. [5]
- (a) Figure 3 shows part of a technical report that incorporates a simple diagram and an
equation. Recreate the report using Microsoft Word ®; the file is to be called “Report.doc”. The document is formatted for an A4 sheet, with a left margin of 3 cm, a right margin of 3 cm and top and bottom margins of 2.5 cm. The default tabs are set to 1 cm. The title is formatted in 14-point bold Times New Roman, while the main text is formatted in 11-point Arial and each paragraph has 12-points clear space before it.[7]
(b) In the same file, recreate the diagram using Word’s drawing tools. [8] (c) In the same file, recreate the equation using Equation Editor ®^. [5]
