Q6- the open circuit and short circuit tests on a 10 KVA, 125/250 v, 50 Hz single phase transformer gave the following results: O.C. Test: 125 V,0.6 A, 50 W ( on L.V.) S.C. Test: 20 V, 40 A, 177.78 W (on H.V. side) Calculate: i) Copper losses on half load ii) Full load efficiency at 0.8 leading p.f. iii) Half load efficiency at 0.8 leading p.f. iv) Regulation at full load at 0.9 leading p.f. Ans: 44.445 W, 97.23%, 97.69%, -1.8015%

Q6- the open circuit and short circuit tests on a 10 KVA, 125/250 v, 50 Hz single phase transformer gave the following results: O.C. Test: 125 V,0.6 A, 50 W ( on L.V.) S.C. Test: 20 V, 40 A, 177.78 W (on H.V. side) Calculate: i) Copper losses on half load ii) Full load efficiency at 0.8 leading p.f. iii) Half load efficiency at 0.8 leading p.f. iv) Regulation at full load at 0.9 leading p.f. Ans: 44.445 W, 97.23%, 97.69%, -1.8015%

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.11MCQ: For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the...

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Similar questions

For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the rated voltage on the other winding? (a) Yes (b) No
In developing per-unit circuits of systems such as the one shown in Figure 3.10. when moving across a transformer, the voltage base is changed in proportion to the transformer voltage ratings. (a) True (b) False
An ideal transformer has no real or reactive power loss. (a) True (b) False
A 250/125 V, five kVA single-phase transformer has a primary resistance of 0.2 ohms and reactance of 0.75 ohms. The secondary resistance is 0.05 ohm and reactance of 0.2 ohms.a) Determine its regulation while supplying full load on 0.8 leading p.f.b) The secondary terminal voltage on full load and 0.8 leading p.f.Ans.: -0.4.88%; 131.1
Full calculation with any assumption needed. All sub questions please as it is all related.
How does change in frequency affect the operation of a given transformer? Ans. 1. Iron loss........ increases with a decrease in frequency. A 60-Hz transformer will have nearly 11% higher losses when worked on 50Hz instead of 60 Hz. However, when a 25-Hz trans- former is worked on 60 Hz, iron losses are reduced by 25%. 2. Cu loss..........in distribution transformers, it is independent of frequecy. 3. Efficiency...........since Cu loss is unaffected by change in frequency, a given transformer effi- ciency is less at a lower frequency than at a higher one. 4. Regulation........regulation at unity power factor is not affected because IR drop is independent of frequency. Since reactive drop is affected, regulation at low power factors decreases with a decrease in frequency and vice-versa. For example, the regulation of a 25-Hz transformer when operated at 50-Hz and low power factor is much poorer. 5. Heating..........since total loss is greater at a lower frequency, the temperature is…
In a transformer that has 10 times more turns on the secondary side (side 2) than on the primary side (side 1), the magnitude of the voltage/EMF across the windings on the secondary side, E₂ will be... O a.... 10 times lower than the voltage/emf on the primary side, E₁. O b.... the same as the voltage/emf on the primary side. O c.... always zero regardless of the voltage on the primary side, E₁. O d.... 10 times higher than the voltage/emf on the primary side, E₁.
Make a conclusion regarding about the topic effect of frequency on transformer rating .
10. In a transformer, the leakage flux of each wind- ing is proportional to the current in that winding because (a) Ohm's law applies to magnetic circuits (b) leakage paths do not saturate (c) the two windings are electrically isolated (d) mutual flux is confined to the core. 11. In a two-winding transformer, the e.m.f.per turn in secondary winding is always.........the induced e.m.f. power turn in primary. (a) equal to K times (b) equal to 1/K times (c) equal to (d) greater than. 12. In relation to a transformer, the ratio 20: 1 indi- cates that (a) there are 20 turns on primary one turn on secondary (b) secondary voltage is 1/20th of primary voltage (c) primary current is 20 times greater than the secondary current. (d) for every 20 turns on primary, there is one turn on secondary.
3. A 3200/400 single-phase transformer has winding resistance and reactance of 30 and 132 respectively in the primary and 0.0292 and 0.0652 in the secondary. Express these in terms of (a) primary alone, (b) secondary alone. (ans. (a) 4.282, 17.16; (b) 0.067, 0.268)
What conclusions we come up with after doing open circuit test on single phase transformer.
9. A single-phase transformer has a turn ratio of 6, the resistances of the primary and secondary windings are 0.9 £2 and 0.025 2 respectively and the leakage reactances of these windings are 5.4 92 and 0.15 2 respectively. Determine the voltage to be applied to the low- voltage winding to obtain a current of 100 A in the short-circuited high voltage winding. Ignore the magnetising current.