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7. The primary and secondary induced e.m.fs. El and E2 in a two-winding transformer are always............ (a) equal in magnitude (b) antiphase with each other (c) in-phase with each other (d) determined by load on transformer secondary 8. A step-up transformer increases... (a) voltage (c) power (b) current (d) frequency. 9. The primary and secondary windings of an ordinary -winding transformer always have...... (a) different number of turns (b) same size of copper wire (c) a common magnetic circuit (d) separate magnetic circuits. 10. The ordinary efficiency of a given transformer is maximum when........... (a) it runs at half full-load (b) it runs at full-load (c) its Cu loss equals iron loss (d) it runs slightly overload. 11. The maximum efficiency of a 100-kVA transformer having iron loss of 900 kW and F.L. Cu loss of 1600 W occurs at ....... kVA. 70 12. The kVA rating of an ordinary 2-winding transformer is increased when connected as an autotransformer because...... (a) 56.3. (b) 133.3 (c)75 (d) 177.7 (a) transformation ratio is increased (b) secondary voltage is increased (c) energy is transferred both inductively and conductivity (d) secondary current is increased. 13. The series field of a short-shunt d.c. generator is excited by (a) shunt. (b) armature. (c) load. (d) external. . Currents 14. In a d.c. generator, the generated e.m.f. is directly proportional to the.......... (a) field current. (b) pole flux. (c) number of armature parallel paths. (d) number of dummy coils.

7. The primary and secondary induced e.m.fs. El and E2 in a two-winding transformer are always............ (a) equal in magnitude (b) antiphase with each other (c) in-phase with each other (d) determined by load on transformer secondary 8. A step-up transformer increases... (a) voltage (c) power (b) current (d) frequency. 9. The primary and secondary windings of an ordinary -winding transformer always have...... (a) different number of turns (b) same size of copper wire (c) a common magnetic circuit (d) separate magnetic circuits. 10. The ordinary efficiency of a given transformer is maximum when........... (a) it runs at half full-load (b) it runs at full-load (c) its Cu loss equals iron loss (d) it runs slightly overload. 11. The maximum efficiency of a 100-kVA transformer having iron loss of 900 kW and F.L. Cu loss of 1600 W occurs at ....... kVA. 70 12. The kVA rating of an ordinary 2-winding transformer is increased when connected as an autotransformer because...... (a) 56.3. (b) 133.3 (c)75 (d) 177.7 (a) transformation ratio is increased (b) secondary voltage is increased (c) energy is transferred both inductively and conductivity (d) secondary current is increased. 13. The series field of a short-shunt d.c. generator is excited by (a) shunt. (b) armature. (c) load. (d) external. . Currents 14. In a d.c. generator, the generated e.m.f. is directly proportional to the.......... (a) field current. (b) pole flux. (c) number of armature parallel paths. (d) number of dummy coils.

Power System Analysis and Design (MindTap Course List)
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 3.9P
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7. The primary and secondary induced e.m.fs. El and E2 in a two-winding transformer are always..... (a) equal in magnitude (b) antiphase with each other (c) in-phase with each other (d) determined by load on transformer secondary 8. A step-up transformer increases... (a) voltage (c) power (b) current (d) frequency. 9. The primary and secondary windings of an ordinary -winding transformer always have........... (a) different number of turns (b) same size of copper wire (c) a common magnetic circuit (d) separate magnetic circuits. 10. The ordinary efficiency of a given transformer is maximum when........... (a) it runs at half full-load (b) it runs at full-load (c) its Cu loss equals iron loss (d) it runs slightly overload. 11. The maximum efficiency of a 100-kVA transformer having iron loss of 900 kW and F.L. Cu loss of 1600 W occurs at ....... kVA. 70 12. The kVA rating of an ordinary 2-winding transformer is increased when connected as an autotransformer because..... (a) 56.3 (b) 133.3 (c)75 (d) 177.7 (a) transformation ratio is increased (b) secondary voltage is increased (c) energy is transferred both inductively and conductivity (d) secondary current is increased. 13. The series field of a short-shunt d.c. generator is excited by............ currents (a) shunt. (b) armature. (c) load. (d) external. 14. In a d.c. generator, the generated e.m.f. is directly proportional to the....... (a) field current. (b) pole flux. (c) number of armature parallel paths. (d) number of dummy coils.
Transcribed Image Text:7. The primary and secondary induced e.m.fs. El and E2 in a two-winding transformer are always..... (a) equal in magnitude (b) antiphase with each other (c) in-phase with each other (d) determined by load on transformer secondary 8. A step-up transformer increases... (a) voltage (c) power (b) current (d) frequency. 9. The primary and secondary windings of an ordinary -winding transformer always have........... (a) different number of turns (b) same size of copper wire (c) a common magnetic circuit (d) separate magnetic circuits. 10. The ordinary efficiency of a given transformer is maximum when........... (a) it runs at half full-load (b) it runs at full-load (c) its Cu loss equals iron loss (d) it runs slightly overload. 11. The maximum efficiency of a 100-kVA transformer having iron loss of 900 kW and F.L. Cu loss of 1600 W occurs at ....... kVA. 70 12. The kVA rating of an ordinary 2-winding transformer is increased when connected as an autotransformer because..... (a) 56.3 (b) 133.3 (c)75 (d) 177.7 (a) transformation ratio is increased (b) secondary voltage is increased (c) energy is transferred both inductively and conductivity (d) secondary current is increased. 13. The series field of a short-shunt d.c. generator is excited by............ currents (a) shunt. (b) armature. (c) load. (d) external. 14. In a d.c. generator, the generated e.m.f. is directly proportional to the....... (a) field current. (b) pole flux. (c) number of armature parallel paths. (d) number of dummy coils.
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