Q.1
When are single phase series universal motors used?
  • When high starting torque is required
  • When starting on no-load is required
  • When constant speeds are required
  • When low speed drives are required
Q.2
When is the stator winding of a three phase squirrel-cage induction motor connected in star?
  • when in full load
  • when running at rated speed
  • when on light load
  • when starting the motor
Q.3
What is the percentage slip of a motor at full load speed where the nameplate details are: f= 50Hz, poles =full load speed =rpm?
  • s = 3%
  • s = 4%
  • s = 5%
  • s = 6%
Q.4
What is the shape of the laminations used in the magnetic circuit of a single phase shell-type transformer?
  • LL
  • TT
  • LE
  • EI
Q.5
What type of transformer is used for interconnecting high voltage transmission systems operating at different voltage levels?
  • Current transformer
  • wound transformer
  • Voltage transformer
  • Autotransformer
Q.6
What conditions must be satisfied before connecting two transformers in parallel to share a common load?
  • Same inductance, same kVA rating
  • Same polarity, same phase sequence
  • Same polarity resistance, same current ratio
  • Same number of polarity turns, same voltage regulation
Q.7
What two power losses occur in a transformer when operating on no-load?
  • Mechanical losses, core losses
  • Frictional losses, heat losses
  • Rotational losses, copper losses
  • Copper losses, core losses
Q.8
What is the danger of opening the secondary circuit of an energized current transformer?
  • High voltage appears across the secondary.
  • Large current flows in the primary.
  • High voltage appears across the primary.
  • Large current flows in the secondary.
Q.9
Which property of a transformer is measured by the change in output voltage from no-load to full-load conditions?
  • voltage ratio
  • transformer efficiency
  • voltage regulation
  • power transfer
Q.10
Why are power transformers operated in parallel?
  • To increase the current rating of the supply.
  • To maximize power supply flexibly.
  • To improve voltage regulation.
  • To reduce heat loss.
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