QUESTION 1: MULTIPLE-CHOICE QUESTIONS
Various options are provided as possible answers to the following questions - NSC Electrical Technology Power Systems - Question 1 - 2021 - Paper 1
Question 1
QUESTION 1: MULTIPLE-CHOICE QUESTIONS
Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A–D)... show full transcript
Worked Solution & Example Answer:QUESTION 1: MULTIPLE-CHOICE QUESTIONS
Various options are provided as possible answers to the following questions - NSC Electrical Technology Power Systems - Question 1 - 2021 - Paper 1
Step 1
1.1 Choose the correct example of an unsafe condition that is likely to cause damage to property or an injury:
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Answer
The best choice is B: Spilling liquid or oil without cleaning it up. This condition poses a risk of slips and falls, which can cause injury or property damage.
Step 2
1.2 An RLC series circuit is predominantly inductive when …
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Answer
The correct answer is A: XC>XL. This indicates that the capacitive reactance is greater than the inductive reactance, leading the circuit to behave inductively.
Step 3
1.3 The phase angle of a predominantly capacitive RLC series circuit is …
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Answer
The answer is A: leading. In a capacitive circuit, the current leads the voltage, resulting in a leading phase angle.
Step 4
1.4 The … of a resonant circuit is the measure of how well it responds to a range of frequencies.
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Answer
The answer is D: selectivity. This term describes the ability of the circuit to respond to specific frequency ranges while ignoring others.
Step 5
1.5 The standard international phase sequence for a three-phase system is …
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Answer
The correct choice is A: red, yellow, blue. This sequence is standard for three-phase systems.
Step 6
1.6 The phase angle between any two phases of a balanced three-phase system is …
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Answer
The answer is C: 120 degrees. In a balanced three-phase system, the phase angle between any two phases is always 120 degrees.
Step 7
1.7 A measuring instrument used to measure electrical energy is a …
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Answer
The correct answer is B: kWh meter. This device measures the electrical energy consumed over time.
Step 8
1.8 A step-up transformer is used to …
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Answer
The answer is D: increase the voltage. Step-up transformers are designed to increase voltage from the primary to the secondary coil.
Step 9
1.9 In three-phase transformers, the transfer of electrical energy from the primary winding to the secondary winding takes place by means of …
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Answer
The correct answer is A: mutual induction. This process allows energy transfer between windings without direct connection.
Step 10
1.10 Which ONE of the following relates to a mechanical inspection of a three-phase motor?
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Answer
The answer is B: Insulation-resistance test between windings. This test checks the insulation integrity of motor windings.
Step 11
1.11 The function of an overload relay in a motor starter control circuit is to …
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Answer
The correct choice is B: deactivate the control circuit and to isolate the power circuit when excessive current flows through the motor. This helps prevent damage.
Step 12
1.12 The speed of rotation of the magnetic field in the stator windings is called … speed.
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Answer
The answer is C: synchronous. This term describes the speed at which the magnetic field rotates in a synchronous machine.
Step 13
1.13 The chronological order of operation for the scan cycle of a PLC is …
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Answer
The proper sequence is A: scan inputs, update process inputs, scan outputs, update outputs. This order ensures the PLC processes data correctly.
