FIGURE 5.1 below shows a three-phase transformer - NSC Electrical Technology Power Systems - Question 5 - 2021 - Paper 1
Question 5
FIGURE 5.1 below shows a three-phase transformer. Answer the questions that follow.
5.1.1 Name parts A and B.
5.1.2 Name TWO possible cooling methods of this trans... show full transcript
Worked Solution & Example Answer:FIGURE 5.1 below shows a three-phase transformer - NSC Electrical Technology Power Systems - Question 5 - 2021 - Paper 1
Step 1
5.1.1 Name parts A and B.
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Answer
Part A is the Oil Conservator (Oil tank), while part B refers to the Bushings (Isolators).
Step 2
5.1.2 Name TWO possible cooling methods of this transformer.
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Answer
Oil Forced Air Cooled
Oil Natural Air Forced
Step 3
5.1.3 List THREE protection devices used in three-phase transformers.
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Inverse definite time relay
Instantaneous overcurrent relay
Buchholz relay
Step 4
5.1.4 Describe the operation of a step-down transformer.
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Answer
A step-down transformer reduces the voltage from the primary to the secondary winding. The primary winding connects to an alternating voltage source, creating an alternating current that induces an alternating magnetic field in the core. This magnetic field induces a smaller alternating voltage in the secondary winding due to Faraday's law of electromagnetic induction. Therefore, the secondary voltage is always lower than the primary voltage, proportional to the turns ratio of the windings.
Step 5
5.2 Name TWO physical characteristics of a three-phase shell-type transformer.
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Answer
The windings are enclosed.
The core structure typically consists of five limbs.
