EE&I QUIZ

The basic function of a transformer is to change A the level of the voltage. B the power level. C the power factor. D the frequency.

Transformer is used A to step up the voltage Transformer is used A to step up the voltage. B to step down the voltage C on dc. D to step up or step down the voltage.

An auto-transformer has A one winding with taps taken out B two interlaced windings. C two windings of same wire. D two windings of different materials. E one winding without taps.

The efficiency of a power transformer is around A 50% B 60% C 80% D 95%

Transformer action requires a A constant magnetic flux Transformer action requires a A constant magnetic flux. B increasing magnetic flux. C alternating magnetic flux. D alternating electric flux.

In a transformer operating at constant voltage, if the input frequency increases, the core loss A increases. B decreases C remains constant. D increases as square of the frequency

The wattage rating for a ceiling motor will be in the range A 50 to 250W. B 250 to 500W. C 50 to 150W. D 10 to 20W

If a dc series motor is operated on ac supply, it A will not start at all B will start and run but will have poor performance such as excessive sparking, poor efficiency and poor power factor C will get damaged due to burning of its windings. D will run at excessively high speed.

A distribution transformer is selected on the basis of A voltage regulation. B efficiency. C all day efficiency. D none of these.

The function of oil in a transformer is A to provide insulation and cooling. B to provide protection against lightning. C to provide protection against short-circuit. D to provide lubrication.

Torque development in a dc motor depends on: A Magnetic field and radius of armature B Current flowing through the armature conductors C Active length of the conductors and number of armature conductors D All the above

A dc motor having full load speed of 750 rpm and speed regulation of 10% will have no load speed of: A 825 rpm B 675 rpm C 800 rpm D 700 rpm

A DC shunt motor is running at light load, what happens if the field winding gets opened? A Motor will stop B Motor will burn C Motor will make noise D Motor will pickup high speed

In an electrical motor, the electromagnetic torque developed is: A In opposite direction to both load torque and fractional torque B In the same direction to the load torque but opposite direction to the fractional torque C In the same direction as the load torque and fractional torque D In the same direction as the fractional torque but in opposite direction to the load torque

The starting torque of dc shunt motor is: A Zero B Low C High D Very high

A DC shunt motor may have rising speed-torque characteristics due to: A Very high armature circuit resistance B Very high field circuit resistance C Very high demagnetizing armature resistance D Very low demagnetizing armature reaction

The dc motor, that has poorest speed regulation is A Cumulative compound B Differential compound C Series D Shunt

If the supply voltage to a dc shunt motor is increased by 15%, which of the following will reduce? A Full load current B Full load speed C Starting torque D None of the above

The speed of dc shunt motor can be increased above its normal speed by: A Increasing the field current B Decreasing the field current C Decreasing the terminal voltage D Increasing the armature resistance

By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor? A Frame B Shaft C Commutator D Stator

A D.C. series motor is that which A has its field winding consisting of thick wire and less turns B has a poor torque C can be started easily without load D has almost constant speed

When two D.C. series motors are connected in parallel, the resultant speed is A more than the normal speed B loss than the normal speed C normal speed D zero

If a D.C. motor is to be selected for conveyors, which motor would be preferred ? A Series motor B Shunt motor C Differentially compound motor D Cumulative compound motor

Which D. C. motor is preferred for elevators Which D.C. motor is preferred for elevators ? A Shunt motor B Series motor C Differential compound motor D Cumulative compound motor

What will happen if the back e. m. f. of a D. C What will happen if the back e.m.f. of a D.C. motor vanishes suddenly? A The motor will stop B The motor will continue to run C The armature may burn D The motor will run noisy