Refer to FIGURE 4.1 below and answer the questions that follow. 4.1.1 State whether the following are step-up or step-down transformers: (a) Transformer at (B) (b) Transformer at (C) 4.1.2 Name the expected voltage provided to the following consumers after transformer (D): (a) Household (b) Industrial 4.1.3 Explain why both household and industrial loads can be powered by transformer (D). 4.1.4 Explain why transformer (B) reduces copper losses in the transmission lines. 4.1.5 Draw a neatly labelled waveform generated at (A) in FIGURE 4.1 above.

NSC Electrical Technology Power Systems Three-Phase Systems: Refer to FIGURE 4.1 below and an

Refer to FIGURE 4.1 below and answer the questions that follow - NSC Electrical Technology Power Systems - Question 4 - 2023 - Paper 1

Question 4

Refer to FIGURE 4.1 below and answer the questions that follow. 4.1.1 State whether the following are step-up or step-down transformers: (a) Transformer at (B) (b) ... show full transcript

Worked Solution & Example Answer:Refer to FIGURE 4.1 below and answer the questions that follow - NSC Electrical Technology Power Systems - Question 4 - 2023 - Paper 1

Step 1

4.1.1 State whether the following are step-up or step-down transformers: (a) Transformer at (B)

96%

114 rated

Answer

Transformer at (B) is a step-up transformer. This transformer increases the voltage for efficient power transmission over long distances.

Step 2

(b) Transformer at (C)

99%

104 rated

Answer

Transformer at (C) is a step-down transformer. It reduces the voltage before distribution to consumers.

Step 3

4.1.2 Name the expected voltage provided to the following consumers after transformer (D): (a) Household

96%

101 rated

Answer

The expected voltage provided to households after transformer (D) is 220 V.

Step 4

(b) Industrial

98%

120 rated

Answer

The expected voltage provided to industrial consumers is 380 V - 415 V.

Step 5

4.1.3 Explain why both household and industrial loads can be powered by transformer (D).

97%

117 rated

Answer

Transformer (D) is connected in star configuration enabling it to create a neutral point. This allows it to supply power to both single-phase (household) and three-phase (industrial) loads efficiently.

Step 6

4.1.4 Explain why transformer (B) reduces copper losses in the transmission lines.

97%

121 rated

Answer

Transformer (B) steps up the voltage which in turn reduces the current flowing through the transmission lines. Since copper losses in the lines are proportional to the square of the current ( $P_{loss} = I^2R$ ), reduced current leads to significantly lower energy losses.

Step 7

4.1.5 Draw a neatly labelled waveform generated at (A) in FIGURE 4.1 above.

96%

114 rated

Answer

Below is a representation of the waveform generated at the generator (A).

       +V
         |                  ----
         |            ----
         |        ----
---------|--------------------
         |       ----
         |            ----
       -V

The waveform above represents a standard sinusoidal waveform, typically expected from an AC generator.

Refer to FIGURE 4.1 below and answer the questions that follow - NSC Electrical Technology Power Systems - Question 4 - 2023 - Paper 1

Worked Solution & Example Answer:Refer to FIGURE 4.1 below and answer the questions that follow - NSC Electrical Technology Power Systems - Question 4 - 2023 - Paper 1

4.1.1 State whether the following are step-up or step-down transformers: (a) Transformer at (B)

(b) Transformer at (C)

4.1.2 Name the expected voltage provided to the following consumers after transformer (D): (a) Household

(b) Industrial

4.1.3 Explain why both household and industrial loads can be powered by transformer (D).

4.1.4 Explain why transformer (B) reduces copper losses in the transmission lines.

4.1.5 Draw a neatly labelled waveform generated at (A) in FIGURE 4.1 above.

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