A 50 Hz transformer having equal hysteresis and eddy current losses at rated excitation is operated at 45 Hz at 90% of its rated voltage. Compared to rated operating point, the core losses under this condition:

A voltage $$V=400$$ sin $$314.16t$$ is applied to a $$1$$-phase transformer on no-load. If the no load current of the transformer is $$2\sin \left( {314.16t - {{85}^0}} \right),\,\,$$ then magnetization branch impedance will be approximately

A $$3$$-phase transformer bank consists of three identical $$2300/230$$ $$V,$$ $$15$$ $$kVA$$ single-phase transformers connected in delta/delta. The bank supplies a $$20$$ $$kVA,$$ unity $$p.f.$$ $$3$$-phase load. If one of the single-phase transformer develops a fault, and is removed, the load carried by each of the two transformers now operating in open delta will be __________$$kVA.$$

A $$220/440$$ $$V,$$ $$50$$ $$Hz$$ single phase transformer operates on $$220$$ $$V,$$ $$40$$ $$Hz$$ supply with secondary winding. Then