eet 4450

In the picture below the light bulb can be seen. It is mounted in the end of the chamber and is fed from the 24 Vdc source in the back of the wooden rack. All components in the enclosure operate at 24 Vdc other than the power cord attached to the power supply.

Figure 2 Chamber's Inside - Showing the Bulb as the Heating Element

The RTD sensor can be seen here. It protrudes into the chamber and is used as the input device for sensing the temperature.

Figure 3 Temperature Measuring - RTD Sensor

Use a rag similar to the one below to insulate and block the exit end of the thermal chamber.

Figure 4 Blue Rag Used to Minimize Heat Loss from the Chamber

Main Tasks for this lab:

1. After power is turned on to the equipment, using the Watlow controller’s display, record the initial temperature in the thermal chamber.

2. Place the output of the controller in the manual mode at 100%. With intervals of 10 seconds between the readings, record the temperature and save this data until the temperature reaches maximum degrees F and the reading is stable for 3 consecutive readings. Graph the data and analyze the data.

3. Turn the controller off and allow the chamber to cool to within 10 degrees of the initial temperature.

4. Repeat Step 2 with the controller set in manual at 70%. With intervals of 10 seconds between the readings, record the temperature and save this data until the temperature reaches maximum degrees F and the reading is stable for 3 consecutive readings. Graph the data and analyze the data.

Questions :

1. From the plots obtained in step 2 and 4, how much time it took to reach the maximum temperature in the chamber for 100% and 70% setting?

2. Provide explanation of why there is a time difference for your answer to Question 1.

4B

Watlow EZ Zone PM Oven Controller

Introduction

The thermal chamber from last week is to be controlled to a set temperature using a single 50 Watt light bulb. In this portion of the lab, the Watlow controller will be used to control the temperature in the chamber to a set temperature.

Procedure

The picture below shows the entire set-up of the thermal chamber with controller. The light bulb can be seen by looking down the tube when the insulation is removed. The controller is attached to the front of the box and is to be used to turn on the light bulb to control temperature in auto mode (variable).

In part 2 of the lab, the controller will be used in the automatic mode .

Use a rag similar to the one below to insulate and block the exit end of the thermal chamber.

Main Tasks for this lab:

Set the temperature controller into auto mode and give a setpoint temperature of 98 degree F. Again, every 10 seconds, record the temperature and save this data until the temperature reaches 98 degrees F, or stabilizes for 3 consecutive readings.

Questions :

1. Graph the data and analyze. Discuss peak, overshoot, settling time and responsiveness of the controller based on the plot.

2. Comment on the action of the controller as the temperature nears the setpoint.

3. Partially remove the insulation to allow some room-temperature air to enter the chamber. Observe the response of the controller and the system, in response to this disturbance.

4. Comment on the action of the controller after the temperature has reached set-point.

5. Report on the automatic settings for your controller including the P, I, and D settings for your controller.

6. Compare these settings to those of other groups around you. How does the P,I and D setting between the two group reflect in the plots? Include the plot and P,I, D numbers of the other group. Compare peak, overshoot, settling time and responsiveness.