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Home⇒ Engineering⇒
Transformers
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ The secondary winding of which of
the following transformers is always
kept closed ? Current transformer [other wrong options] [Discuss in forum] Step-up transformer Step-down transformer Potential transformer |
Q22 ⇒ Which of the following is not the standard
voltage for power supply in India ? 122 kV [other wrong options] [Discuss in forum] 11 kV 33 kV 66 kV |
Q23 ⇒ A good voltage regulation of a transformer
means output voltage fluctuation from no load to full load is least [other wrong options] [Discuss in forum] output voltage fluctuation with
power factor is least difference between primary and secondary voltage is least difference between primary and secondary voltage is maximum |
Q24 ⇒ Which of the following is the most likely
source of harmonics in a transformer ? Core saturation [other wrong options] [Discuss in forum] Poor insulation Overload Loose connections |
Q25 ⇒ If a transformer is switched on to a
voltage more than the rated voltage its power factor will deteriorate [other wrong options] [Discuss in forum] its power factor will increase its power factor will remain unaffected its power factor will be zero |
Q26 ⇒ A trahsformer is working at its maximum
efficiency. Its iron loss is 1 kW. Its
copper loss will be 1 kW [other wrong options] [Discuss in forum] 0.2 kW 0.25 kW 0.5 kW |
Q27 ⇒ A transformer having a turn ratio 1 : 5
and a resistance of 1000 ohms is connected
across the secondary terminals, the
resistahce offered to a current flowing
in the primary will be 40 Ω [other wrong options] [Discuss in forum] 10 Ω 20 Ω 60 Ω |
Q28 ⇒ The iron losses of a transformer can be
calculated by knowing the weights of cores and yokes [other wrong options] [Discuss in forum] copper winding only yokes only cores only |
Q29 ⇒ Buchholz relay is used on oil cooled transformers [other wrong options] [Discuss in forum] welding tran.sformers air-cooled transformers furnace transformers |
Q30 ⇒ In a transformer frictional loss is nil [other wrong options] [Discuss in forum] 5% of total loss 10% of total loss 20% of total loss |
Q31 ⇒ For power purpose sine wave shape is
preferred because it is stable wave shape as the line parameters cannot change it [other wrong options] [Discuss in forum] it gives least copper losses it is easy to generate e.m.f. of this wave shape none of the above |
Q32 ⇒ Cross-over windings are used for high voltage winding of small rating transformers [other wrong options] [Discuss in forum] high voltage winding of l arge rating
transformers low voltage winding of small rating transformers none of these |
Q33 ⇒ The reactance of a transformer depends
on leakage flux [other wrong options] [Discuss in forum] size of the core size of the tank all of the above |
Q34 ⇒ In which of the following transformer
part of primary winding also serves as
the secondary winding ? Auto transformer [other wrong options] [Discuss in forum] Potential transformer Step-up transformer Current transformer |
Q35 ⇒ Transformer cores are built-up from
laminations rather than from solid
metal so that eddy current loss is reduced [other wrong options] [Discuss in forum] less insulation is required for the
windings oil penetrates the core more easily turn ratio is higher than voltage ratio |
Q36 ⇒ In large transformers, oil is invariably
used in order to insulate the coils [other wrong options] [Discuss in forum] lubricate the core insulate the core none of the above |
Q37 ⇒ In order to find the full-load efficiency
of a transformer the losses which must
be known may be found by performing opencircuit and short-circuit tests [other wrong options] [Discuss in forum] may be found by measuring winding
resistances and calculating the
I2R losses may be found by measuring the input to the primary with secondary open cannot be found except by actually loading the transformer fully. |
Q38 ⇒ In which of the following the highest
rating transformer is likely to find
application ? Generator [other wrong options] [Discuss in forum] Transmission Sub station Distribution |
Q39 ⇒ In a transformer the energy is
conveyed from primary to secondary by the flux [other wrong options] [Discuss in forum] through cooling coil through air none of the above |
Q40 ⇒ Sumpner's test is conducted on transformers
to determine temperature [other wrong options] [Discuss in forum] stray losses all-day efficiency none of the above |
Or |