DC Motors
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens

This will make armature to take heavy current, possibly burning it
Nothing will happen to the motor
This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
Motor will run at very slow speed

ANSWER DOWNLOAD EXAMIANS APP

DC Motors
In a dc compound machine,

Shunt field winding plays dominant role
Both play equally dominant role
Series field winding plays dominant role
Either can play dominant role

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DC Motors
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens

This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
Motor will come to stop
Nothing will happen to motor
This will make armature to take heavy current, possibly burning it

ANSWER DOWNLOAD EXAMIANS APP