MCQOPTIONS
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MCQOPTIONS
This section includes 120 Mcqs, each offering curated multiple-choice questions to sharpen your ENGINEERING SERVICES EXAMINATION (ESE) knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The thickness of a 50 Hz transformer lamination is |
| A. | 0.35 mm |
| B. | 0.35 cm |
| C. | 0.30 cm |
| D. | 0.33 m |
| Answer» B. 0.35 cm | |
| 102. |
Transformer core usually uses grain-oriented laminated sheets. The grain orientation reduces |
| A. | Eddy current loss |
| B. | Copper loss |
| C. | None of the above |
| D. | Hysteresis loss |
| Answer» B. Copper loss | |
| 103. |
During parallel operation of transformers incorrect polarity will result in |
| A. | Dead short circuit |
| B. | Open circuit |
| C. | Power factor of transformer will be different from that of the connected load |
| D. | Regeneration of power |
| Answer» B. Open circuit | |
| 104. |
The value of flux in the emf equation of a transformer is |
| A. | Average |
| B. | rms |
| C. | Integral wave cycle |
| D. | Maximum |
| Answer» E. | |
| 105. |
If a load on secondary side of a transformer increases, the current on the primary side |
| A. | Increases |
| B. | Remains constant |
| C. | None of these |
| D. | Decreases |
| Answer» B. Remains constant | |
| 106. |
A 400/100 V, 10 kVA two-winding transformer is reconnected as an autotransformer across a suitable voltage source. The maximum kVA is |
| A. | 15 kVA |
| B. | 50 kVA |
| C. | 8.75 kVA |
| D. | 12.5 kVA |
| Answer» C. 8.75 kVA | |
| 107. |
In operating a 400 Hz transformer at 50 Hz |
| A. | Only kVA is reduced in the same proportion as the frequency |
| B. | Only voltage is reduced in the same proportion as the frequency |
| C. | None of the above |
| D. | Both voltage and kVA rating are reduced in the same proportion as the frequency |
| Answer» E. | |
| 108. |
In the circuit model of a transformer, the core loss is represented as |
| A. | Series inductance |
| B. | Series resistance |
| C. | Shunt inductance |
| D. | Shunt resistance |
| Answer» E. | |
| 109. |
High leakage impedance transformers are used for applications such as |
| A. | Electrical toys |
| B. | Power distribution |
| C. | Fluorescent lamps |
| D. | Arc welding |
| Answer» E. | |
| 110. |
Laminated insulations coated with varnish are normally used in the transformer |
| A. | To reduce the effect of eddy current |
| B. | nated insulations coated with varnish are normally used in the transformer ( To reduce reluctance of magnetic path |
| C. | To reduce the hysteresis effect |
| D. | To increase the reluctance of magnetic path |
| Answer» B. nated insulations coated with varnish are normally used in the transformer ( To reduce reluctance of magnetic path | |
| 111. |
A transformer 2,000 kVA, 250 Hz is operated at 50 Hz. Its kVA rating should be revised to |
| A. | 10,000 kVA |
| B. | 400 kVA |
| C. | Cannot be revised |
| D. | 2,000 kVA |
| Answer» C. Cannot be revised | |
| 112. |
If 110 per cent of normal voltage and 110 per cent of normal frequency is applied to a transformer, the percentage change of eddy current losses will be |
| A. | 0.2 |
| B. | 0.1 |
| C. | 0.21 |
| D. | 0.25 |
| Answer» D. 0.25 | |
| 113. |
A 10 kVA, 400/200 V sinlge-phase transformer with 10 per cent impedance draws a steady short circuit line current of |
| A. | 150 A |
| B. | 50 A |
| C. | 350 A |
| D. | 250 A |
| Answer» E. | |
| 114. |
The cross-sectional area of the common portion of an autotransformer is |
| A. | Proportionally decreased |
| B. | Kept constant |
| C. | None of these |
| D. | Proportionally increased |
| Answer» B. Kept constant | |
| 115. |
Transformer humming sound is reduced by the |
| A. | Proper insulation |
| B. | Proper bracing of transformers assemblies |
| C. | Proper design of winding |
| D. | Proper design |
| Answer» C. Proper design of winding | |
| 116. |
The efficiency of a transformer is usually in the range of |
| A. | 65–75% |
| B. | 50–60% |
| C. | 90–98% |
| D. | 70–90% |
| Answer» D. 70–90% | |
| 117. |
A transformer used only for electrical isolation between two circuits has turns ratio which is |
| A. | Less than unity |
| B. | More than unity |
| C. | More than 0.5 |
| D. | Equal to unity |
| Answer» E. | |
| 118. |
The flux involved in the emf equation of a transformer has |
| A. | Average value |
| B. | rms value |
| C. | Maximum value |
| D. | Total value |
| Answer» D. Total value | |
| 119. |
The transformer which will have the largest size is |
| A. | 100 kVA, 100 Hz |
| B. | 100 kVA, 25 Hz |
| C. | 100 kVA, 60 Hz |
| D. | 100 kVA, 50 Hz |
| Answer» B. 100 kVA, 25 Hz | |
| 120. |
The leakage flux in a transformer depends upon the value of |
| A. | Supply frequency |
| B. | Load current |
| C. | None of these |
| D. | Mutual flux |
| Answer» C. None of these | |