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Department of Electrical Engineering
EM and MI
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Question 1 : The errors in currents transformers can be reduced by designing them with
Option-1 :large primary ampere-turns
Option-2 :primary & secondary windings wound with large cross-section
Option-3 :primary & secondary windings wound closed together
Option-4 :both (a) & (c)
Question 2 : Clamp-on ammeter is used for measurement of
Option-1 :large alternating current
Option-2 :small alternating current
Option-3 :small direct current
Option-4 :large direct current
Question 3 : The secondary of a CT is never left open circuited because otherwise
Option-1 :heat dissipation in the core will be very large
Option-2 :the core will be saturated and permanently magnetised rendering it useless
Option-3 :dangerously high emfs will be induced in the secondary
Option-4 :all of the above
Question 4 : The primary current in a current transformer is dictated by
Option-1 :the secondary burden
Option-2 :the core of the transformer
Option-3 :the load current
Option-4 :none of the above
Question 5 : The advantages of instrument transformers over ammeter shunts and voltmeter multipliers are
Option-1 :the metering circuit is electrically isolated from the power thereby providing safety in use to both the instruments and the operator
Option-2 :small power losses in comparison to those in ammeter shunts and voltmeter multipliers
Option-3 :the instrument transformers can be used for both dc as well as ac measurements
Option-4 :both (a) & (b)
Question 6 : The burden of current transformers is expressed in
Option-1 :volt-ampere rating
Option-2 :current rating of secondary winding
Option-3 :current & voltage of secondary
Option-4 :watt rating
Question 7 : The number of turns on the primary of current transformer is usually
Option-1 :1 to 5
Option-2 :10 to 20
Option-3 :20 to 100
Option-4 :100 to 500
Question 8 : The main requirements of voltage multipliers to be used for dc measurements are
Option-1 :low temperature coefficient
Option-2 :the resistance shouldnot change with time of usage
Option-3 :there should be ample provision for cooling to dissipate the heat developed
Option-4 :all of the above
Question 9 : The function of a shunt in an ammeter is to
Option-1 :increase the instrument resistance
Option-2 :bypass the current
Option-3 :reduce the voltage drop across the instrument coil
Option-4 :increase the current flowing through the instrument coil
Question 10 : Measuring range of voltmeter can be extended by using
Option-1 :high shunt resistance
Option-2 :high series resistance
Option-3 :low shunt resistance
Option-4 :low series resistance
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