1. Find the all-day effiency of a 50 kVA distribution transformer having fll load efficiency of...

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1. Find the all-day effiency of a 50 kVA distribution transformer having fll load efficiency of 94 % and full-load copper losses are equal to the constant iron losses. The loading of the transformer is as follows, the power factor being 1.0.: () No load for 10 hours (i) Half load for 5 hours (i)25 % load for 6 hours (iv) Full load for 3 hours. 2. Two 11,000/2,200-V, 1-phase transformers are connected in parallel to supply a total load of 250 at 0.8 p.f. lagging at 2,200 V. One transformer has an equivalent resistance of 0.4 Q and equivalent reactance of 0.8 Q referred to the low-voltage side. The other has equivalent resistance of 0.1Q and a reactance of 0.30. Determine the current and real power supplied by each transformer. 3. Two transformers A and B are connected in parallel to supply a load having an impedance of (2 + j 1.50). The equivalent impedances referred to the secondary windings are 0.15 + j 0.5 Q and 0.1 + j0.6 Q respectively. The open-circuit EMF of A is 207 V and of B is 205 V. Calculate () the voltage at the load (i) the power supplied to the load (ii) the power output of each transformer and (iv) the kVA input to each transformer. 1. Find the all-day effiency of a 50 kVA distribution transformer having fll load efficiency of 94 % and full-load copper losses are equal to the constant iron losses. The loading of the transformer is as follows, the power factor being 1.0.: () No load for 10 hours (i) Half load for 5 hours (i)25 % load for 6 hours (iv) Full load for 3 hours. 2. Two 11,000/2,200-V, 1-phase transformers are connected in parallel to supply a total load of 250 at 0.8 p.f. lagging at 2,200 V. One transformer has an equivalent resistance of 0.4 Q and equivalent reactance of 0.8 Q referred to the low-voltage side. The other has equivalent resistance of 0.1Q and a reactance of 0.30. Determine the current and real power supplied by each transformer. 3. Two transformers A and B are connected in parallel to supply a load having an impedance of (2 + j 1.50). The equivalent impedances referred to the secondary windings are 0.15 + j 0.5 Q and 0.1 + j0.6 Q respectively. The open-circuit EMF of A is 207 V and of B is 205 V. Calculate () the voltage at the load (i) the power supplied to the load (ii) the power output of each transformer and (iv) the kVA input to each transformer.