semester 4 lab 2 experiment 1

7/27/2019 Semester 4 Lab 2 Experiment 1

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FAKULTI KEJURUTERAAN ELEKTRIK

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BEKC 2421

CONTROL SYSTEM ENGINEERING LABORATORY

EXPERIMENT 2:

TEMPERATURE CONTROL SYSTEM (Part 1)

Group Members : HO WAH CHONG B011110299

: LING SING YIP B011210094

: KOH GUAN KEONG B011110245

Lab Group : G2

Program/Section : 2BEKM/S1

Date : 29/04/2013

Checked By :

Score :



Part 1: Temperature Control System

1.0 Abstract The experiment in part 1 was aim to study about the temperature control system. In the

experiment in part 1, there are two parts; one part is study about the open-loop temperature

control system, another part is study about the Positive and Negative Feedback in Closed-

Loop Temperature Control System. The method that we used during the experiment is by

using the Lab-Volt Process Control Trainer Model 3521 to do out the experiment. The Lab-

Volt Process Control Trainer Model 3521 is an apparatus that can set up the basic

temperature control system by using heater, fan and temperature indicator.

2.0 Objective and Scope1. To observe and explain the operation of open-loop and closed-loop temperature control

system.

2. To compare the performance characteristics of the open-loop and closed-loop temperaturecontrol system.

3.0 Experiment BackgroundControl system consists of an input, a process, and an output. Control system can be

differentiating into 2 types, which are open-loop and close-loop. Open-loop system output for

disturbances is not monitored or corrected whereas in closed-loop system is monitored and

compared with input so that if an error is detected, the system will correct the output and

hence corrects the effects of disturbances. However, open-loop systems are simpler and less

expensive than closed-loop system. [1]

While in temperature control system, the main thing that we control is the temperature. The

examples that related to our daily in the temperature control system is the air-conditional. We

can set the temperature that we desired in the system. When the sensor detect the

environmental temperature is different with the temperature that we set in the system. The

air-conditional will change the temperature by blowing more cold air into the environment or

stop blowing any cold air into environment. The main thing that we study in this experiment

is related to the car radiator temperature control system. The Lab-Volt Process Control

Trainer model 3521 will act as the car radiator temperature control system.

4.0 Equipment1. Lab-Volt Process Control Trainer Model 3521

2. Connecting Leads

3. Stopwatch



Figure 1: The Lab-Volt Process Control Trainer Model 3521

Figure 2: The diagram show the circuit of an open-loop temperature control system



5.0 Open-Loop Temperature Control System5.1 Procedure

1. The appropriate connection as the circuit shown in the Figure 2 which is an open-loop

temperature control system is made.

2. The POWER switch to ON position is set and the initial temperature of the radiator is

recorded.3. The DC SOURCE-1-LEVEL control to voltage set point at +2.5v is turned on. The

temperature of the radiator of every minute is recorded for 15 minutes or until the

temperature stabilizers occur. The light of the Solid State Relay LED is also observed.

4. After 15 minutes or temperature stabilizers occur, the Fan Speed switch to high position is

set to increase the heat loss from the radiator.

5. The temperature of the radiator is recorded for every 10minutes or until the temperature

stabilizers.

6. The DC-SOURCE-1-LEVEL control is turned into fully counterclockwise to cut the power

supply to the heater.

7. The table of the result is shown to show the relationship between the temperature of the

radiator and time. The time when the fan is switched on is indicated.

8. The Power of the Process Control Trainer is turned off and all the leads are removed when

temperature display is approximately equal to the room temperature

5.2 Result

Time(minute) Temperature(oC) Solid State Relay

0 27.5 Off

1 31.8 Off

2 35.7 On

3 39.1 On4 41.8 On

5 43.6 On

6 45.0 On

7 45.3 On

8 45.5 On

9 45.5 On

10 45.6 On

11 45.7 On

12 45.7 On

13 45.7 On

14* 44.0 On

15 43.2 Off

16 42.9 Off

17 42.8 Off

18 42.8 Off

19 42.8 Off

20 42.8 Off

* The fan start to switch on.



0

5

10

15

20

25

30

35

40

45

50

1Min 2Min 3Min 4Min 5Min 6Min 7Min 8Mn 9Min 10Min 11Min 12Min 13Min

Graph of the Radiator's Temperature Increase

42.2

42.4

42.6

42.8

43

43.2

43.4

43.6

43.8

44

44.2

14Min 15Min 16Min 17Min 18Min 19Min 20Min

Graph of the Radiator's Temperature Decrease



6.0 Positive and Negative Feedback in Closed-Loop Temperature Control

System6.1 Procedure

Figure 3: The diagram show the circuit of the closed-loop temperature control

1. The appropriate connection as the circuit shown in the Figure 3 which is an closed-loop

temperature control system is made.

2. The following settings on the trainer are set:

DC Source-1-Level - Fully counterclockwise(MIN)

Temperature Transmitter Zero - Mid position

Temperature Transmitter Span - Min.

DC Voltmeter Input Selector - High

Level Comparator Hysteresis - MinHeater Power - High

Fan Speed - High

Proportional Amplifier Gain - ¼ of maximum

Limiter Level - Max.

3. The trainer is turned ON and the set point voltage, V of +3.5v is set.

4. The feedback voltage, VT the error voltage, VE and the amplified error voltage, Vo are

measured by using the B input of the DC voltmeter.

5. The system is operated until the temperature display indicated approximately 35oC. The

error voltage, VE during this time interval is observed.

6. The feedback voltage, VT the error voltage, VE and the amplified error voltage, Vo aremeasured again by using the B input of the DC voltmeter.



7. The DC-SOURCE-1-LEVEL control is turned into fully counterclockwise to cut the power

supply.

8. The Power of the Process Control Trainer is turned off when temperature display is

approximately equal to the room temperature.

Figure 4: The diagram show the circuit use in the second part

9. The connections on the trainer are modified to obtain the circuit shown in Figure 4.

10. The feedback voltage, VT the error voltage, VE and the amplified error voltage, Vo are

measured again by using the B input of the DC voltmeter.

11. The system is operated for a 5 minutes to observe the error voltage.

12. The lead connected to the control input of the Solid State Relay and the trainer is operated

few minutes so that the temperature of the radiator decreases.

13. The Power is switch off of the trainer and removes all leads.

6.2 Result VT(v) VE(v) Vo(v)

Trainer Just On 0.5 2.5 5.125

Temperature reach 35oC 3.5 0 0

The voltage shut down 3 6.3 5.5

5Minutes after the shut down 4.5 6.7 5.5



7.0 Discussion7.1 Open-Loop Temperature Control System

From this experiment, we can see that when the power of the heater switches on, the

temperature of radiator increases. When the temperature reaches 45.7oC, the temperature

remains constant at that moment because the heat transfers out and in the radiator has

remained constant. After 14 minutes the power switches on, we switch on the fan to colddown the radiator by increasing the heat loss from the radiator.

7.2 Positive and Negative Feedback in Closed-Loop Temperature Control System

7.3 Precaution

1. Connecting circuit is permitted only after power has been disconnected to avoid electric

shock. After finishing the connection of experiment circuit or doing any modification on the

experiment circuit, please ask the instructor to verify whether it is right or not before turning

on the power supply.

2. Always choose sufficiently long leads; do not connect two or more short leads to make one

long lead. Remove disconnected lead from the trainer.

3. Before proceed with different test, let the system operate and wait until the temperature

display is approximately equal to the room temperature.

8.0 Conclusion

10.0 References[1] Nur Aidawaty Rafan and Silah Hayati Kamsani, Control Systems Theory, Module 4,

Universiti Teknikal Malaysia Melaka, 2011.

semester 4 lab 2 experiment 1

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