Transformer GATE 2024 Fundamental Quiz

A 2800V/280V auto transformer is shown in the figure below has its primary coil A B connected to the common line at point C. The secondary side is between D and C. Now if there is disconnection between the terminal B and C, while the transformer is energised at the primary side with 2800V. The auto transformer is loaded so that the rated current of the windings are not exceeded. What is the voltage V₂ of the secondary side?

The maximum efficiency (in percentage) at unity power factor for 2500/ 250V, 20KVA, 1-phase transformer is __

Consider core loss = 50 W and Ohmic loss at loading = 100 W

Consider Y/Δ (3-ϕ) step down transformer. What is output kVA if Primary voltage = 11 kV and Secondary current = 423A; Tums ratio = 5

Consider the circuit as shown in figure below:

Find the value of output voltage, V_out is _______ V. (round off to up to two decimal places).

Two identical 1–ϕ transformer of 15 kVA, gave the following results, when tested by back to back method.

W₁ = 1000 watt (Primary)

W₂ = 1500 watt (Secondary)

Calculate the percentage efficiency of transformer at 1/4^th load 0.8 P.F. lag