D.C. Motors

Constant torque drive Constant voltage drive Constant current drive None of the above Single phase capacitor start Induction motor Synchronous motor D.C. motor Low cost Wide speed range Stability High starting torque Of lower H.P. should be selected Of higher H.P. should be selected Can be used for 50°C ambient temperature also Is to be de-rated by a factor recommended by manufacturer and select the next higher H.P. motor Damage to commutator segments Damage to commutator insulation Increased power consumption All of the above Shunt motor Series motor Differential computed D.C. motor Cumulative compound D.C. motor Starter for a car Drive for a water pump Fan motor Motor operation in A.C. or D.C. Trains Cranes Hoists Machine tools Regenerative Plugging Dynamic braking None of the above Lenz’s law Faraday’s law Coulomb’s law Fleming’s left-hand rule Independent of armature current Directly proportional to the armature current Proportional to the square of the current Inversely proportional to the armature current As separately wound unit In parallel with armature winding In series with armature winding In parallel with field winding Proportional to the armature current Proportional to the square of the armature current Proportional to field current Inversely proportional to the armature current More than the normal speed Loss than the normal speed Normal speed Zero These motors have high starting torque These motors are not self-starting Back e.m.f. of these motors is zero initially To restrict armature current as there is no back e.m.f. while starting