Various options are provided as possible answers to the following questions - NSC Electrical Technology Power Systems - Question 1 - 2022 - Paper 1
Question 1
Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1... show full transcript
Worked Solution & Example Answer:Various options are provided as possible answers to the following questions - NSC Electrical Technology Power Systems - Question 1 - 2022 - Paper 1
Step 1
1.1 A/N ... is an occurrence when a serious or unexpected dangerous situation occurs that requires immediate attention.
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Answer
The correct answer is A. This situation clearly describes a critical scenario that demands immediate action, which aligns with the definition of an "evacuation procedure."
Step 2
1.2 The total opposition against the flow of alternating current in an RLC circuit is the ...
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Answer
The answer is B. Impedance represents the total opposition to the flow of alternating current in an RLC circuit, combining both resistance and reactance.
Step 3
1.3 When decreasing frequency to below resonance in a series RLC resonance circuit, the ...
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Answer
The answer is A. In this case, impedance increases and the circuit becomes inductive, as reactance influences the total impedance.
Step 4
1.4 The opposition to AC current flow caused by a capacitor will increase when the ...
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Answer
The answer is B. Increasing frequency causes a decrease in reactance for capacitors, thereby reducing opposition to current flow.
Step 5
1.5 An advantage of a three-phase system is that ...
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Answer
The appropriate answer is D. A three-phase system is typically more economical than single-phase systems due to efficiencies in power distribution.
Step 6
1.6 Power that is transferred backwards and forwards between the supply and the inductor or capacitor without doing any work is known as ... power.
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Answer
The correct answer is B. Reactive power represents the power that oscillates between the source and the reactive components without performing any work.
Step 7
1.7 In an electric power system, a load with a low power factor draws ... current from the supply compared with a load with a high power factor.
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Answer
The answer is A. A load with a low power factor draws less real power compared to its apparent power than one with a high power factor.
Step 8
1.8 When comparing three-phase transformers to single-phase transformers, a ...
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Answer
The best answer is C. Three-phase transformers can efficiently power both single-phase and three-phase loads.
Step 9
1.9 A Buchholz relay will activate and isolate the transformer from the supply when ...
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Answer
The correct answer is A. A severe fault will cause gas to form within the transformer oil, triggering the Buchholz relay.
Step 10
1.10 An advantage of a three-phase motor over a single-phase motor is that a three-phase motor ...
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Answer
The right choice is D. Three-phase motors generally require less maintenance due to their design and efficiency.
Step 11
1.11 Refer to the typical speed versus the torque characteristic curve of a three-phase motor. The breakdown torque is ... the full-load torque.
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Answer
The breakdown torque is higher than the full-load torque, which ensures that the motor can start under load without stalling.
