SPRING 2005

NAME______________________________ Please attach and place your name on any extra pages used. You may use your text (Smith and Corripio) for this exam. If you find an error in this exam extra credit will be allowed for a creative solution.

1. The following ladder logic diagram describes the control wiring of a combustion system which uses an electric igniter to initiate combustion. Describe how and in what sequence the blower, fuel valve, and igniter are energized.

2. Use direct substitution to determine the ultimate gain and frequency for the following system and recommend settings for a PID controller for the system that would produce quarter amplitude decay response.

3. Given the following Bode Diagram, Determine Gain Margin. Indicate on the diagram the margin. Assuming the diagram was drawn for a controller gain of 1, what would the ultimate gain (Ku) of the system be? What would the ultimate frequency be? Estimate the initial PID controller settings to deliver quarter amplitude decay ratio performance.

4.

Use root locus analysis to examine stability in the system described by the following block diagram. Based on the root locus diagram, will the system ever:

1) oscillate? 2) not oscillate? 3) become instable?