A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 Ω and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

Electrical Machines
A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 Ω and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

2 .1 Ω

3.1 Ω

1.8 9 Ω

1.79 Ω

2 .1 Ω

3.1 Ω

1.8 9 Ω

1.79 Ω

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Electrical Machines
In case the conditions for maximum power for DC motor are established, the efficiency of the motor will be

Around 100 %.

Less than 50 %

Any where between 75 % and 90 %.

Around 90 %

Around 100 %.

Less than 50 %

Any where between 75 % and 90 %.

Around 90 %

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Electrical Machines
The armature resistance of the dc motor is generally of the range

100 ohm.

0.5 ohm.

50 ohm.

0.1 ohm.

100 ohm.

0.5 ohm.

50 ohm.

0.1 ohm.

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Electrical Machines
The brush-axis of a bipolar dc motor is rotated by 90°. The effect of this rotation on the back emf Eband the torque developed Tdwould be such that

both Eb and Td are unchanged

Eb is zero, but Td is unchanged

both Eb and Td are zero

Eb is unchanged, but Td is zero

both Eb and Td are unchanged

Eb is zero, but Td is unchanged

both Eb and Td are zero

Eb is unchanged, but Td is zero

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Electrical Machines
Addition of 0.3 % to 4.5 % silicon to iron

increases the hysteresis loss.

increases the electrical resistivity of iron.

None of these

reduces the saturation magnetization.

increases the hysteresis loss.

increases the electrical resistivity of iron.

None of these

reduces the saturation magnetization.

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Electrical Machines
The ___________________ generator has the poorest voltage regulation.

shunt.

under-compounded.

over compounded.

differential compounded.

shunt.

under-compounded.

over compounded.

differential compounded.

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Electrical Machines

Electrical Machines A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 Ω and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

Electrical Machines In case the conditions for maximum power for DC motor are established, the efficiency of the motor will be

Electrical Machines The armature resistance of the dc motor is generally of the range

Electrical Machines The brush-axis of a bipolar dc motor is rotated by 90°. The effect of this rotation on the back emf Eband the torque developed Tdwould be such that

Electrical Machines Addition of 0.3 % to 4.5 % silicon to iron

Electrical Machines The ___________________ generator has the poorest voltage regulation.

Electrical Machines
A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 Ω and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

Electrical Machines
In case the conditions for maximum power for DC motor are established, the efficiency of the motor will be

Electrical Machines
The armature resistance of the dc motor is generally of the range

Electrical Machines
The brush-axis of a bipolar dc motor is rotated by 90°. The effect of this rotation on the back emf Eband the torque developed Tdwould be such that

Electrical Machines
Addition of 0.3 % to 4.5 % silicon to iron

Electrical Machines
The ___________________ generator has the poorest voltage regulation.