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
Consider a separately excited DC motor. If the field current is increased while the armature terminal voltage is held constant, then speed of the motor

Decrease.

None of these.

Remains same.

Increase.

Decrease.

None of these.

Remains same.

Increase.

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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/4Sp²

PZL/4S

PZL/4Sa²

PZL/ 4Sa

PZL/4Sp²

PZL/4S

PZL/4Sa²

PZL/ 4Sa

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Electrical Machines
In a DC Shunt Motor if the load current increases then field flux

decreases

decreases.

remains constant.

increases.

decreases

decreases.

remains constant.

increases.

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Electrical Machines
Which of the following load normally needs starting torque more than rated torque?

Air compressors.

Blowers.

Conveyers.

Centrifugal pumps.

Air compressors.

Blowers.

Conveyers.

Centrifugal pumps.

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Electrical Machines
A transformer core is made up of a silicon steel laminations which has maximum flux density 1 Tesla. If it was cold rolled grain oriented its flux density increases to 1.6 Tesla. What is the saving in core size or area due to cold rolled grain oriented process?

68%

40%

38%

60%

68%

40%

38%

60%

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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 Consider a separately excited DC motor. If the field current is increased while the armature terminal voltage is held constant, then speed of the motor

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 In a DC Shunt Motor if the load current increases then field flux

Electrical Machines Which of the following load normally needs starting torque more than rated torque?

Electrical Machines A transformer core is made up of a silicon steel laminations which has maximum flux density 1 Tesla. If it was cold rolled grain oriented its flux density increases to 1.6 Tesla. What is the saving in core size or area due to cold rolled grain oriented process?

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
Consider a separately excited DC motor. If the field current is increased while the armature terminal voltage is held constant, then speed of the motor

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
In a DC Shunt Motor if the load current increases then field flux

Electrical Machines
Which of the following load normally needs starting torque more than rated torque?

Electrical Machines
A transformer core is made up of a silicon steel laminations which has maximum flux density 1 Tesla. If it was cold rolled grain oriented its flux density increases to 1.6 Tesla. What is the saving in core size or area due to cold rolled grain oriented process?