Electrical Machines Magnetic field of a DC generator is produced by what? Both B and C. Permanent magnets. None of the options. Electromagnets. Both B and C. Permanent magnets. None of the options. Electromagnets. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The brushes of a DC machine should be placed on the commutator in the polar axis. armature midway between poles. commutator in the inter polar axis. armature in the polar axis. commutator in the polar axis. armature midway between poles. commutator in the inter polar axis. armature in the polar axis. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The direction of generated emf in the armature coil of a DC machine is 1. the same as that of the current in a generator 2. the same as that of the current in a motor 3. opposite to that of the current in a generator 4. opposite to that of the current in a motor From these, the correct answer is 1, 4 1, 3 2, 3 2, 4 1, 4 1, 3 2, 3 2, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is 31.9 Ω 31.1 Ω 15.1 Ω 15.9 Ω 31.9 Ω 31.1 Ω 15.1 Ω 15.9 Ω ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The compensating winding in a DC machine is located on pole shoes to avoid the sparking at the brushes. is located on commutating poles for improving commutation. is located on pole shoes for avoiding the flashover at the commutator. is located in armature slots for compensation of the armature reaction. is located on pole shoes to avoid the sparking at the brushes. is located on commutating poles for improving commutation. is located on pole shoes for avoiding the flashover at the commutator. is located in armature slots for compensation of the armature reaction. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines With the increase in speed of DC motor Both back emf as well as line current fall. Both back emf as well as line current increase. Back emf increase but line current falls. Back emf falls and line current increase. Both back emf as well as line current fall. Both back emf as well as line current increase. Back emf increase but line current falls. Back emf falls and line current increase. ANSWER DOWNLOAD EXAMIANS APP
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