Q5:Choose the correct answer from the given alternatives 4. A transformer has negative voltage regulation when its load power factor is: (a) zero (b) lagging. (d) unity (c) leading 5. During short-circuit test, the iron loss of a transformer is negligible because: (a) the entire input is just sufficient to meet Cu losses only (b) flux produced is a small fraction of the normal flux (c) iron core becomes fully saturated (d) supply frequency is held constant. 6. At relatively light loads, transformer efficiency is low because: (a) secondary output is low (b) fixed loss is high in proportion to the output (d) Cu loss is small. (c) transformer losses are high 7. The saving in Cu achieved by converting 2-winding transformer into an autotransformer is determined by: (a) voltage transformation ratio (b) magnetic quality of core material (c) load on the secondary (d) size of the transformer core.

Q5:Choose the correct answer from the given alternatives 4. A transformer has negative voltage regulation when its load power factor is: (a) zero (b) lagging. (d) unity (c) leading 5. During short-circuit test, the iron loss of a transformer is negligible because: (a) the entire input is just sufficient to meet Cu losses only (b) flux produced is a small fraction of the normal flux (c) iron core becomes fully saturated (d) supply frequency is held constant. 6. At relatively light loads, transformer efficiency is low because: (a) secondary output is low (b) fixed loss is high in proportion to the output (d) Cu loss is small. (c) transformer losses are high 7. The saving in Cu achieved by converting 2-winding transformer into an autotransformer is determined by: (a) voltage transformation ratio (b) magnetic quality of core material (c) load on the secondary (d) size of the transformer core.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

See similar textbooks

Similar questions

If we increase the load than core loss and copper loss will... Decrease Increase Remain same
None
During the load test of single-phase transformer, when the secondary terminal voltage increases, the regulation of the transformer will ................?(complete)
B/ Fill in the blanks: 1. The purpose of providing the iron core in the transformer is to 2. A transformer transforms... 3. Power transformers are designed to have maximum efficiency at 4. The transformer ratings are usually expressed in terms of menm
4. The portion of the flux that goes through one of the transformer coils but not the other one is called. A) Average flux B) Mutual flux D) Leakage flux C) Total flux 5. The fundamental component of the magnetization current ------- the voltage applied to the core by ------ 90°: A) Lags, 45° B) Leads, 45°. D). Leads, 90°. C) Lags, 90°. 6. The ----- are resistive heating losses in the core of the transformer. A) Hysteresis losses. B) Copper losses. C) Leakage flux losses. D) Eddy current losses. 7. The total rotational losses of an induction motor are a combination of: A) Friction losses B) Windage losses. C) Core losses. D) Stray losses. 8. Induction motors are now the preferred A) absence of brushes. choice for industrial motors due to B) Small size. C) Less control requirements. D) rugged construction. 9. For an induction motor, if the synchronous speed is 1800 r/m, and the rotor speed 180rad/sec, then the slip will be: A) 5.5 % C) 6% B) 4.5% D) 4% 10. The lower the speed of an…
The cross-sectional area of a transformer limb is 80 cm² and the volume of the transformer core is 5000 cm³. The maximum value of the core flux is 10 mWb at a frequency of 50 Hz. Taking the Steinmetz constant as 1.7, the hysteresis loss is found to be 100 W. Determine the value of the hysteresis loss when the maximum core flux is 8 mWb and the frequency is 50 Hz.
A 5750 V/ 260 V, 50HZ single-phase transformer is to have an approximate e.m.f. per turn of 35 V and operate with a maximum value of flux density of 1 T. Calculate (a) the number of primary turns (b) number of secondary turns (c) maximum value of flux and (d) the cross-sectional area of the core. Number of turns in Primary Number of turns in Secondary maximum value of flux Area of cross section
Q5:Choose the correct answer from the given alternatives (answer five only) 1.In an ideal transformer, (a) windings have no resistance (b) core has infinite permeability (d) all of the above. (c) core has no losses 2. The primary and secondary induced e.m.fs. El and E2 in a two-winding transformer are always: (a) equal in magnitude (b) in-phase with each other (c) antiphase with each other (d) determined by load on transformer secondary. 3. In relation to a transformer, the ratio 20 : 1 indicates 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. 4. A transformer has negative voltage regulation when its load power factor is: (a) zero (b) lagging. (d) unity (c) leading
Q1: During the separation of transformer core losses experiment: 1. Why should always keep the ratio of V/F constant? 2. If the transformer is operated at rated frequency but at voltage lower than rated value, how do you expect the following quantities to change? And why? i. Hysteresis loss ii. Eddy current loss iii. No-load current