It is desired to measure parameters of $$230$$ $$V/115$$ $$V,$$ $$2$$ $$kVA$$, single-phase transformers. The following watt-meters are available in a laboratory:
$${W_1}:250\,\,V,\,\,\,10\,\,A,\,\,\,\,\,\,$$ Low Power Factor
$${W_2}:250\,\,V,\,\,\,5\,\,A,\,\,\,\,\,\,$$ Low Power Factor
$${W_3}:150\,\,V,\,\,\,10\,\,A,\,\,\,\,\,\,$$ High Power Factor
$${W_4}:150\,\,V,\,\,\,5\,\,A,\,\,\,\,\,\,$$ High Power Factor

The watt-meters used in open circuit test and short circuit test of the transformer will respectively be

In a transformer, zero voltage regulation at full load is

In transformers, which of the following statements is valid?

Which three-phase connection can be used in a transformer to introduce a phase difference of 30° between its output and corresponding input line voltages