Class 4 (4th Engineer) MET 📅 Sep 2022

Exam Question

(a) Describe a simple single-phase transformer (8)

(b) A 15 kVA, 440/110-volt, 50 cycle/sec, Single-phase transformer has primary and secondary resistances of 0.12 ohm and 0.0077 ohm respectively. The iron loss of the transformer is 0.16 kW Calculate the efficiency of the transformer

(i) on full load unity power factor

(ii) on 80 per cent full load at a power factor of 0.9 lagging. (10)

Reference Answer

**Part (a) Simple Single-Phase Transformer**
A transformer is a static electrical device that transfers electrical energy from one circuit to another through the principle of electromagnetic induction, without a change in frequency. It is used to 'step-up' (increase) or 'step-down' (decrease) AC voltage levels.
### 1. Principle of Operation
The operation of a transformer is based on **Faraday's Law of Electromagnetic Induction** and **Mutual Induction**.

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