A single phase 5 KVA, 200/400 V, 50 Hz transformer has core loss 150 W and full load copper loss of 175 W. Calculate the efficiency of the transformer at 75% loading with 0.7 power factor.

Find the value of R₁ for maximum power transfer through R₁. Also find the maximum power.

Four voice signals each limited to 4 kHz and sampled at Nyquist rate are converted into binary PCM signal using 256 quantization levels. Find the bit transmission rate for the time-division multiplexed signal.

What are the conditions of parallel operation of 3 phase transformers?