1. The turn ratio of a 220 V AC to 24 V AC step down transformer must be
(a) 9.1.
(b) 5.13.
(c) 0.109.
(d) 0.513. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
2. Which of the following loss in a transformer is zero even at full load ?
(a) Core loss.
(b) Friction loss.
(c) Eddy current loss.
(d) Hysteresis loss. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
3. When the full load of a transformer is reduced to half full load, its copper losses are
(a) reduced by half.
(b) reduced by four time.
(c) remain unchanged.
(d) double. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
4. When the full load of a transformer is reduced to half full load, the iron losses are
(a) reduce by half
(b) reduce by four time
(c) remain same
(d) double [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
5. The hum in a transformer is mainly attributed to
(a) load changes.
(b) oil in the transformer.
(c) magnetostriction.
(d) mechanical vibrations. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
6. In which transformer, the territory winding is used?
(a) star delta.
(b) delta star.
(c) delta delta.
(d) star star. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] D [/accordion-item][/accordion]
7. A no-load test on a transformer is conducted to determine
(a) core loss.
(b) copper loss.
(c) efficiency.
(d) magnetising current and loss. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] D [/accordion-item][/accordion]
8. The primary and secondary winding of an auto-transformer are
(a) electrically coupled.
(b) magnetically coupled.
(c) both of the above.
(d) none of the above. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
9. The no load current in a transformer lags behind the applied voltage by an angle of about
(a) 180°.
(b) 90°.
(c) 75°.
(d) 30°. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
10. In the circuit model of transformer the copper loss can be represented as
(a) series resistance.
(b) shunt resistance.
(c) shunt inductance.
(d) series inductance. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] A [/accordion-item][/accordion]
11. The main function of conservator in a transformer is to
(a) provide fresh air to transformer.
(b) supply cooling oil to transformer.
(c) protect the transformer from damage when oil expends due to heating.
(d) absorb moisture from air. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] C [/accordion-item][/accordion]
12. Auto transformer can be good choice if the transformation ratio is
(a) more than one.
(b) near to one.
(c) less than one.
(d) near to zero. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
13. Transformer breaths in when
(a) load on it increases..
(b) load on it decreases.
(c) load remains constant.
(d) none of the above. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
14. An ideal transformer does not change
(a) voltage.
(b) power.
(c) current.
(d) all of the above. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] B [/accordion-item][/accordion]
15. When the leakage flux in a transformer is increases, its secondary induce e.m.f. is
(a) decreases.
(b) increases.
(c) remain same.
(d) none of the above. [accordion clicktoclose=true tag=h4][accordion-item title=”Answer” state=closed] A [/accordion-item][/accordion]