Automation Technology

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Document No : UniKL Revision No: 02 Effective Date: 01 Dec

SUBJECT SUBJECT LEVEL TIME / DU DATE

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SEPTEMBER 2013 CONFIDENTIAL

FAB 11203 AUTOMATION TECHNOLOGY 1

SECTION A (Total: 40 marks)

INSTRUCTION: Answer ALL questions.

Please use the answer booklet provided.

Question 1

(a) Describe three (3) types of signal that associated in automatic control system.

(3 marks) (b) Explain the general functions of pneumatic pre-actuator in any control system.

(2 marks) (c) Suggest the most suitable sensor for each application in Figure 1.

(6 marks)

i.

Application: Detection of translucent packs

ii.

Application: Liquid level detection on a water supply tube

iii.

Application: Detection of low- reflective work pieces such as black rubber

iv.

Application: Detecting yellow marks on labels

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SEPTEM

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(4)

Question 2

(a) Explain briefly the protection against high voltage in signal conditioning can be obtained by using Opto-Isolator as exampled in Figure 3.

(5 marks)

Figure 3: Opto-Isolator application

(b) Suggest one (1) type of analog sensor or digital sensor that could be used to measure below condition:

i. The flow of conductive waste water ii. Level of bulk solids

iii. Track the position of motor shaft iv. Airspeed in aircraft

(4 marks) (c) State the advantages of using multi position cylinder compared to two position

cylinders. Propose the suitable pneumatic pre-actuator to be used to control this kind of cylinder.

(3 marks) (d) Complete the truth table in Table 1 by referring to logic circuit in Figure 4.

Figure 4: Logic circuit

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Table 1: Truth table of logic function

A B C Y

0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

(8 marks)

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Answer the following questions:

i. Calculate the net voltage of the thermocouple if it produces 50mV at 1400C and 10mV at 200C.

(2 marks) ii. Describe the operation of thermocouple.

(4 marks) iii. Resistance Temperature Detector (RTD) is another type of temperature

sensor with the purpose to detect a change in a resistance parameter that corresponds to a temperature change. List two (2) advantages of thermocouple compared to RTD.

(2 marks) iv. The temperature transducer has an input module between 0V to 10V and receives a valid signal from a thermocouple that can detect temperature range from -20C to 650C. The transducer then will produce current signal 4- 20mA to a controller. Find the output current at temperature 100 C.

(7 marks) v. Suggest the suitable controller for this system. Justify your answer.

(3 marks) vi. The converter converts an input current of 4-20 mA into pressure parameter that range from 3 to 15 psi. Determine the output pressure when giving input current of 14mA.

(4 marks)

(b) Figure 6 below shows an example of CNC machine for automatically controlling machines using servo motors. Answer the following questions.

Figure 6: CNC controller

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i. List four (4) types of CNC machine in general manufacturing industry and their function.

(4 marks) ii. CNC controller can be divided into two types of movement; Point to Point

Movement and Continuous Path Movement. Discuss both of them in terms of operation or application.

(4 marks)

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Question 4

(a) Answer the following questions according to the system description.

Figure 7: Bottling System

System Operation:

The servo drive system in Figure 7 compares the position of the bottles from sensor S2 and send the feedback signal to the controller to indicate the position of the filling carriage that is mounted to the ball screw. Sensor S3 will send signals to confirm on the bottle presence. The servo drive amplifier will increase or decrease the speed of the ball-screw mechanism so that the nozzles will match the speed of the bottles exactly. Sensor S1 will determine the bottle liquid level and conveyor run forward to next workstation.

i. Determine the suitable type of S1, S2, S3, and the possible controller, pre- actuator, actuator and input components to be used in this system.

(7 marks) ii. Draw the functional block diagram that describes the relationship between each

component.

(3 marks)

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iii. If the manufacturer would like to upgrade this system into producing three or four similar products in batches; e.g. Liquid A in first week, Liquid B in second week and Liquid C in third week, give your recommendation on how it can be implemented by using the same equipment. The only differences are liquid composition and cycle time. State the benefits of your recommendation.

(5 marks)

(b) In Figure 8, an incremental rotary encoder is being used to monitor the direction and measure length of paper produced in a production line.

Figure 8: Rotary encoder system in paper production line

i. Given the optical disc radius, r is 450 mm and the precision, P is 3 mm, find the best number of pulse per revolution (resolution) N of the encoder. Several encoder resolution N manufactured are N = 1000, N = 2000, N = 3000.

(4 marks) ii. Using answer in Qb(i), if the encoder receive channel A = 1100, calculate the

length of film that been produced. Given maximum linear speed Vz = 1.5m/s.

(4 marks) iii. If the disc shaft is attached to the motor shaft with reduction gear system

(ratio 3:1), find the rotational angle of those motor shaft.

(2 marks) iv. Discuss the differences between incremental encoder and absolute encoder.

(5 marks) Encoder

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Question 5

(a) Figure 9 shows a system to sort NG (incomplete) product from good product. The product consists of a metal sphere and its holder made from fiber glass. This system consists of a conveyor moved by 3-phase motor, a sensor S1 and S2, three pilot lamps (L1, L2, and L3), two bins and a double acting cylinder, Cylinder A.

When a start push button, St is pressed, the conveyor will on. Operator of the system will place the product at Drop Zone. The product will then be transferred to Inspection Post to check either the product is completed or not. If the product is detected as good by S1, it will be transferred directly to good product bin. If not good, the lamp L1, L2 and L3 will ON. At reject post, Cylinder A will extend as to push reject part to reject bin. S2 will count for the NG products and stop the conveyor when the quantity reaches 30 pieces. The system will stop when a stop push button, Sp is pressed.

Figure 9: Part Inspection System

i. S1 and S2 are the same type of sensor. Suggest the suitable sensor based on the description given. Justify your answer.

(2 marks) Part OK

Reject Bin

Cylinder A

S1

Drop Zone

Inspection Post

Encoder

L1 L2 L3

S2

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ii. Construct the control wiring diagram for this station.

(12 marks) iii. If an encoder has been mounted to the drive shaft of the conveyor, determine its function and the suitable type of encoder to perform the function. Describe its operation.

(4 marks)

(b) Figure 10 shows a direct control circuit of a single acting cylinder. Answer the following questions.

i. Identify the type of pneumatic pre-actuator in this figure. Determine whether it is a Normally Open or Normally Closed type. Justify your answer.

(3 marks) ii. Describe the operation of this control circuit.

(4 marks) iii. If the single acting cylinder is replaced with double acting cylinder, provide

your recommendation on the pre-actuator type and controlling circuit.

(5 marks)

Figure 10: Control of a Single acting cylinder

END OF QUESTION