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

1.8 9 Ω

3.1 Ω

2 .1 Ω

1.79 Ω

1.8 9 Ω

3.1 Ω

2 .1 Ω

1.79 Ω

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Electrical Machines
For a DC machine having P no of pair of pole pairs, Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance?

PZL/ 4Sa

PZL/4Sp²

PZL/4S

PZL/4Sa²

PZL/ 4Sa

PZL/4Sp²

PZL/4S

PZL/4Sa²

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Electrical Machines
Armature reaction in a DC machine

is in the same direction as the main poles.

makes an angle of 90° with the main pole axis.

makes an angle with the main pole axis which is load dependent.

is in direct opposition to the main poles.

is in the same direction as the main poles.

makes an angle of 90° with the main pole axis.

makes an angle with the main pole axis which is load dependent.

is in direct opposition to the main poles.

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Electrical Machines
The slip of an induction motor normally does not depend on

rotor speed.

synchronous speed.

shaft torque.

core loss component.

rotor speed.

synchronous speed.

shaft torque.

core loss component.

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Electrical Machines
For higher values of armature, the speed of a DC series motor is

Proportional to armature current.

Constant.

Inversely proportional to armature current.

Proportional to the square of armature current.

Proportional to armature current.

Constant.

Inversely proportional to armature current.

Proportional to the square of armature current.

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

increases the hysteresis loss.

reduces the saturation magnetization.

None of these

increases the electrical resistivity of iron.

increases the hysteresis loss.

reduces the saturation magnetization.

None of these

increases the electrical resistivity of iron.

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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 For a DC machine having P no of pair of pole pairs, Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance?

Electrical Machines Armature reaction in a DC machine

Electrical Machines The slip of an induction motor normally does not depend on

Electrical Machines For higher values of armature, the speed of a DC series motor is

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

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
For a DC machine having P no of pair of pole pairs, Z no of conductors having length L of resistivity ρ and cross section S are arranged. what is the armature resistance?

Electrical Machines
Armature reaction in a DC machine

Electrical Machines
The slip of an induction motor normally does not depend on

Electrical Machines
For higher values of armature, the speed of a DC series motor is

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