DC Motors
The main disadvantage of the Ward-Leonard control method is

High initial cost
High maintenance cost
All of these
Low efficiency at high loads

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

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

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