Q1. A 100 kVA, 6.6kV/415V, single phase transformer has an effective impedance of (3+8j) Ώ referred to HV side. Estimate the full load voltage regulation at 0.8 pf lagging and 0.8 leading pf.
Q2. 12. A 20 KVA, 2400/240V, 50Hz two winding transformer has an efficiency of 97.5% at full load, 0.8 Pf. It is connected as a 2400/2640 V auto transformer. (i) What are the other different possible connections as an auto transformer? (ii) For the auto transformer mentioned above, at full load calculate the kVA output. , kVA transformered & kVA conduted. Find also the efficiency at full load, unity power factor. (iii) Ratio of weight of auto transformer conductors to weight of conductors in two winding transformer.
Answers
Zol 3+j8r voltage regulation at 0.8pf lag & o. 8pf lead 801 100KNA , 6.6 kv/415V Refer to tv side: Roi = 32 Xoi=82 full load 100x 10 1 ? 3 6. 6X10 la) 3 15.15 vouage regulation at lagging pf = "R, Coso,+ 1, X, sino, % V.R VI 15.15 x 3x0.8t 15.15 x 8 x 0.6 6.6610 XIOD 1.652% at leading pf %V.R= 1,...
Answer:
1. 3.A100 kVA, 6.6kV/415V, single phase transformer has an effective impedance of (3+8j) ? referred to HV side. Estimate the full load voltage regulation at 0.8 pf lagging and 0.8 leading pf. (16) 4.(a)Explain the working of auto transformer and prove that when transformation ratio approaches unity, the amount copper used approaches smaller value. (8) (b)The emf per turn of a single phase, 6.6kV/440V, 50 Hz transformer is approximately 12V. Calculate the number of turns in the HV and LV windings and the net cross sectional area of the core for a maximum flux density of 1.5T
