A single-phase 400 V, 50 Hz transformer has an iron loss of 5000 W at the condition. When operated at 200 V, 25 Hz, the iron loss is 2000 W. When operated at 416 V, 52 Hz, the value of the hysteresis loss divided by the eddy current loss is ________.

If the star side of the star-delta transformer shown in the figure is excited by a negative sequence voltage, then

A single-phase, 22 kVA, 2200 V/220 V, 50 Hz, distribution transformer is to be connected as an autotransformer to get an output voltage of 2420 V. Its maximum kVA rating as an auto-transformer is

Two single-phase transformers T₁ and T₂ each rated at 500 kVA are operated in parallel. Percentage impedances of T₁ and T₂ are (1 + j6) and (0.8 + j4.8), respectively. To share a load of 1000 kVA at 0.8 lagging power factor, the contribution of T₂ (in kVA) is ________.