6.1 Describe the following terms with reference to PLCs:
6.1.1 Hardware
6.1.2 Software
6.1.3 Opto-coupler
6.2 List THREE important hardware components of a PLC - NSC Electrical Technology Power Systems - Question 6 - 2020 - Paper 1
Question 6
6.1 Describe the following terms with reference to PLCs:
6.1.1 Hardware
6.1.2 Software
6.1.3 Opto-coupler
6.2 List THREE important hardware components of a PLC.
6... show full transcript
Worked Solution & Example Answer:6.1 Describe the following terms with reference to PLCs:
6.1.1 Hardware
6.1.2 Software
6.1.3 Opto-coupler
6.2 List THREE important hardware components of a PLC - NSC Electrical Technology Power Systems - Question 6 - 2020 - Paper 1
Step 1
6.1.1 Hardware
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Answer
Hardware refers to all the physical components of the PLC, including the CPU, input/output modules, and physical connections.
Step 2
6.1.2 Software
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Answer
Software refers to the programs installed on the PLC that enable it to perform specific tasks, including the operating system and configuration software.
Step 3
6.1.3 Opto-coupler
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Answer
An opto-coupler is a component that uses light to transmit signals between isolated circuits, providing electrical isolation between input and output.
Step 4
6.2 List THREE important hardware components of a PLC.
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Answer
Central Processing Unit (CPU)
Input/Output (I/O) modules
Power supply unit
Step 5
6.3 State THREE safety precautions to be considered when connecting a PLC to the supply.
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Answer
Ensure that correct wiring and connections are checked before connecting the PLC.
Use appropriate fuses or circuit breakers for protection.
Verify that the power supply voltage matches the PLC specifications.
Step 6
6.4(a) Draw the logic gate symbol of the ladder logic circuit in FIGURE 6.4.
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The logic gate symbol for the ladder logic circuit consists of a series configuration where the contacts A and B are connected to the coil Q in parallel.
Step 7
6.4(b) Complete the truth table in FIGURE 6.4.2 below by writing ONLY the state of the output on the ANSWER SHEET FOR QUESTION 6.4.2.
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Answer
OUTPUT Q
0 (0,0)
0 (0,1)
0 (1,0)
1 (1,1)
Step 8
6.5 State ONE application of an inductive proximity sensor.
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Inductive proximity sensors are commonly used for counting metal objects on a production line.
Step 9
6.6.1 State whether the logic program represents an ON-delay timer contact or an OFF-delay timer contact.
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The logic program represents an ON-delay timer contact.
Step 10
6.6.2 Describe the sequential operation of the logic program when the push button (I1) is pressed.
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Once the push button is pressed, the timer (TD) is energized, activating the normally open contact. The output (Q) remains low while the timer accumulates time. After 15 seconds, the timer resets, and the output (Q) returns to high when the push button is released.
Step 11
6.8.1 State the conditions of the red lamp and the green lamp before the start button is pressed.
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Before the start button is pressed, the red lamp will be OFF and the green lamp will be OFF.
Step 12
6.8.2 Explain the function of MC in the circuit.
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MC (contactor) functions to actuate the mechanism. When energized, MC closes the contacts, allowing current to flow to the lamp circuits.
Step 13
6.9 Explain the principle or operation of the variable speed drive (VSD).
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A variable speed drive controls the speed of an electric motor by varying the frequency and voltage of the power supplied to the motor.
Step 14
6.11.1 Describe the duration of the switching time at area A and area B with reference to pulse width modulation in FIGURE 6.11.
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Area A has a shorter switching time compared to Area B, which has a longer switching time. This difference is critical for the modulation of the output signal.
Step 15
6.11.2 State the effects the width of the pulses has on the average output voltage in FIGURE 6.11 A.
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The greater the width of the pulses, the higher the average output voltage. This affects the performance and control of the motor.
Step 16
6.12 State THREE precautions that must be considered when working with a VSD.
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Avoid using long cable runs to reduce losses.
Ensure proper grounding for safety.
Follow manufacturer installation guidelines to prevent electrical hazards.
