Class 4 (4th Engineer) MET 📅 Aug 2025

Exam Question

(a) Discuss the open circuit and short circuit test performed for transformer. (6)

(b) The primary and secondary windings of a 30 KVA, 76000/230 V, 1 ph transformer have resistance of 10 Ω and 0.016 Ω respectively. The reactance of the transformer referred to the primary is 34 Ω. Calculate the primary voltage required to circulate full load current when the secondary is short circuited. What is the power factor on the short circuit? (10)

Reference Answer

### (a) Open Circuit and Short Circuit Tests for a Transformer
These two tests are essential for determining the parameters of a transformer's equivalent circuit, its efficiency, and voltage regulation without actually loading the transformer to its full capacity.
#### 1. Open Circuit (O.C.) or No-Load Test
This test is performed to determine the no-load losses (core/iron losses) and the no-load current parameters (magnetizing and core loss components).

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