Electrical Machines The material used for commutator brushes is mostly cast iron. mica. copper. carbon. cast iron. mica. copper. carbon. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines To increase starting torque of a 3-phase slip ring induction motor, preferred method is to increase None of these supply frequency supply voltage rotor resistance None of these supply frequency supply voltage rotor resistance ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The residual magnetism of a self-excited dc generator is lost. To build up its emf again the armature connection must be reversed field winding must be excited by low voltage dc supply the field winding must be replaced the field winding connection must be reversed the armature connection must be reversed field winding must be excited by low voltage dc supply the field winding must be replaced the field winding connection must be reversed ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Compensating winding is placed in the pole shoe armature core main field All of these pole shoe armature core main field All of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The sparking at the the brushes, in a DC machines is due to high resistance of carbon brushes. reactance voltage. presence of commutator. armature reaction. high resistance of carbon brushes. reactance voltage. presence of commutator. armature reaction. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc shunt motor has external resistance Ra and Rf in the armature and field circuits respectively. Armature current at starting can be reduced by keeping Rf maximum and Ra minimum Ra maximum and Rf maximum Ra maximum and Rf minimum Ra minimum and Rf minimum Rf maximum and Ra minimum Ra maximum and Rf maximum Ra maximum and Rf minimum Ra minimum and Rf minimum ANSWER DOWNLOAD EXAMIANS APP
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