Transformers — Part 2 MCQs with Explanations

air core is the correct answer to “The core used in high frequency transformer is usually”. This question is standard in competitive examination syllabi for Transformers.

infinite is the correct answer to “In a transformer the resistance between its primary and secondary is”. This question is standard in competitive examination syllabi for Transformers.

on leading power factor is the correct answer to “A transformer can have regulation closer to zero”. This question is standard in competitive examination syllabi for Transformers.

nearly full load is the correct answer to “Power transformers are designed to have maximum efficiency at”. This question is standard in competitive examination syllabi for Transformers.

$${{\text{B}}_{\max }}^{1.6}$$ is the correct answer to “Hysteresis loss in a transformer varies as (B max = maximum flux density)”. This question is standard in competitive examination syllabi for Transformers.

75° is the correct answer to “The no load current in a transformer lags behind the applied voltage by an angle of about”. This question is standard in competitive examination syllabi for Transformers.

back-to-back test is the correct answer to “The efficiency of two identical transformers under load conditions can be determined by”. This question is standard in competitive examination syllabi for Transformers.

unity power factor is the correct answer to “For a transformer, operating at constant load current, maximum efficiency will occur at”. This question is standard in competitive examination syllabi for Transformers.

low voltage side of high kVA transformers is the correct answer to “Helical coils can be used on”. This question is standard in competitive examination syllabi for Transformers.

less will be the secondary induced e.m.f. is the correct answer to “Greater the secondary leakage flux”. This question is standard in competitive examination syllabi for Transformers.

thin coat of varnish is the correct answer to “The transformer laminations are insulated from each other by”. This question is standard in competitive examination syllabi for Transformers.

electrical fault inside the transformer itself is the correct answer to “Buchholz's relay gives warning and protection against”. This question is standard in competitive examination syllabi for Transformers.

$$\frac{{{{\text{R}}_2}}}{{{{\text{K}}^2}}}$$ is the correct answer to “If R 2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be”. This question is standard in competitive examination syllabi for Transformers.

per unit impedance is the correct answer to “Two transformers operating in parallel will share the load depending upon their”. This question is standard in competitive examination syllabi for Transformers.

Frequency is the correct answer to “Which of the following does not change in an ordinary transformer”. This question is standard in competitive examination syllabi for Transformers.

core flux density is increased is the correct answer to “When a given transformer is run at its rated voltage but reduced frequency, its”. This question is standard in competitive examination syllabi for Transformers.

Frequency is the correct answer to “Which of the following does not change in a transformer”. This question is standard in competitive examination syllabi for Transformers.

low is the correct answer to “The starting torque of a squirrel-cage induction motor is”. This question is standard in competitive examination syllabi for Transformers.

Low voltage side is the correct answer to “While conducting short-circuit test on a transformer the following side is short circuited”. This question is standard in competitive examination syllabi for Transformers.

the voltage applied on primary side is low is the correct answer to “During short circuit test iron losses are negligible because”. This question is standard in competitive examination syllabi for Transformers.

windings is the correct answer to “If a transformer is continuously operated the maximum temperature rise will occur in”. This question is standard in competitive examination syllabi for Transformers.

20 V is the correct answer to “The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 Ω load. The turns ratio is 3:1. What is the secondary voltage”. This question is standard in competitive examination syllabi for Transformers.

reduces weight per kVA is the correct answer to “The use of higher flux density in the transformer design”. This question is standard in competitive examination syllabi for Transformers.

lags behind the voltage by about 75° is the correct answer to “No-load current in a transformer”. This question is standard in competitive examination syllabi for Transformers.

To decrease the magnitude of magnetizing current is the correct answer to “The purpose of providing iron core in a step-up transformer is”. This question is standard in competitive examination syllabi for Transformers.

122 kV is the correct answer to “Which of the following is not the standard voltage for power supply in India”. This question is standard in competitive examination syllabi for Transformers.

in parallel is the correct answer to “When the equivalent circuit diagram of doouble squirrelcage induction motor is constructed the two cages can be considered”. This question is standard in competitive examination syllabi for Transformers.

false is the correct answer to “An ideal transformer has infinite values of primary and secondary inductances. The statement is”. This question is standard in competitive examination syllabi for Transformers.

primary is supplied rated voltage is the correct answer to “During open circuit test of a transformer”. This question is standard in competitive examination syllabi for Transformers.

Radio interference test is the correct answer to “Which of the following is not a routine test on transformers”. This question is standard in competitive examination syllabi for Transformers.

much higher is the correct answer to “The efficiencies of transformers compared with that of electric motors of the same power are”. This question is standard in competitive examination syllabi for Transformers.

Hum is the correct answer to “The noise resulting from vibrations of laminations set by magnetic forces, is termed as”. This question is standard in competitive examination syllabi for Transformers.

main flux device is the correct answer to “The power transformer is a constant”. This question is standard in competitive examination syllabi for Transformers.

temperature is the correct answer to “Sumpner's test is conducted on transformers to determine”. This question is standard in competitive examination syllabi for Transformers.

same polarity is the correct answer to “For the parallel operation of single phase transformers it is necessary that they should have”. This question is standard in competitive examination syllabi for Transformers.

both (B) and (C) is the correct answer to “In a transformer routine efficiency depends upon”. This question is standard in competitive examination syllabi for Transformers.

magnetising current and loss is the correct answer to “No-load on a transformer is carried out to determine”. This question is standard in competitive examination syllabi for Transformers.

33 kV is the correct answer to “The dielectric strength of transformer oil is expected to be”. This question is standard in competitive examination syllabi for Transformers.

moisture is the correct answer to “A transformer oil must be free from”. This question is standard in competitive examination syllabi for Transformers.

friction and windage losses is the correct answer to “Losses which occur in rotating electric machines and do not occur in trans formers are”. This question is standard in competitive examination syllabi for Transformers.