NSC Electrical Technology Power Systems Transformer Principles: Gegee: TR = 5 : 1 V1 = 2 000 V S

Gegee: TR = 5 : 1 V1 = 2 000 V S = 50 kVA Puit = 45 kW Transformatorverliese = 500 W Bereken die: 4.7.1 Sekondêre fase spanning 4.7.2 Rendement van die transformator 4.7.3 Arbeidsfaktor van die transformator 4.7.4 Stroom deur die las getrek - NSC Electrical Technology Power Systems - Question 4 - 2021 - Paper 1

Question 4

Gegee:-TR-=-5-:-1-V1-=-2-000-V-S-=-50-kVA-Puit-=-45-kW-Transformatorverliese-=-500-W--Bereken-die:--4.7.1-Sekondêre-fase-spanning--4.7.2-Rendement-van-die-transformator--4.7.3-Arbeidsfaktor-van-die-transformator--4.7.4-Stroom-deur-die-las-getrek-NSC Electrical Technology Power Systems-Question 4-2021-Paper 1.png

Gegee: TR = 5 : 1 V1 = 2 000 V S = 50 kVA Puit = 45 kW Transformatorverliese = 500 W Bereken die: 4.7.1 Sekondêre fase spanning 4.7.2 Rendement van die transforma... show full transcript

Worked Solution & Example Answer:Gegee: TR = 5 : 1 V1 = 2 000 V S = 50 kVA Puit = 45 kW Transformatorverliese = 500 W Bereken die: 4.7.1 Sekondêre fase spanning 4.7.2 Rendement van die transformator 4.7.3 Arbeidsfaktor van die transformator 4.7.4 Stroom deur die las getrek - NSC Electrical Technology Power Systems - Question 4 - 2021 - Paper 1

Step 1

Sekondêre fase spanning

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Answer

To find the secondary phase voltage $V_{2}$ , we use the transformer turns ratio:

V_{2} = \frac{N_{2}}{N_{1}} \times V_{1}

Given:

$N_{1} = 5$ , $N_{2} = 1$ , and $V_{1} = 2000 V$ :

V_{2} = \frac{1}{5} \times 2000 = 400 V

Therefore, the secondary phase voltage is 400 V.

Step 2

Rendesment van die transformator

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Answer

The efficiency $\, \eta$ of the transformer can be calculated using the formula:

\eta = \frac{P_{uit}}{P_{uit} + verlies} \times 100

Where:

$P_{uit} = 45000 W$ (45 kW) and $verlies = 500 W$ :

\eta = \frac{45000}{45000 + 500} \times 100 = 98.9\%

Thus, the efficiency of the transformer is 98.9%.

Step 3

Arbeidsfaktor van die transformator

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Answer

The power factor $\cos \theta$ is determined using the following equation:

\cos \theta = \frac{P}{S}

Where:

$P = 45000 \, W$ and $S = 50000 \, VA$ (50 kVA):

\cos \theta = \frac{45000}{50000} = 0.9

So, the power factor is 0.9.

Step 4

Stroom deur die las getrek

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Answer

To find the current through the load $I_{2}$ , we use the formula:

I_{2} = \frac{S}{\sqrt{3} \times V_{2} \times \cos \theta}

Substituting the values:

$S = 50000 \, VA$ and $V_{2} = 400 \, V$ accordingly:

I_{2} = \frac{50000}{\sqrt{3} \times 400 \times 0.9} = 72.17 \, A

Thus, the current drawn by the load is approximately 72.17 A.

Sekondêre fase spanning

Rendesment van die transformator

Arbeidsfaktor van die transformator

Stroom deur die las getrek

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