Consider the following statements : For a level compounded dc generator to run at constant voltage, the series field mmf must effectively compensate 1. armature reaction mmf 2.armature resistance drop 3. brush contact voltage drop Which of these statements is/are correct ?

Electrical Machines
Consider the following statements : For a level compounded dc generator to run at constant voltage, the series field mmf must effectively compensate 1. armature reaction mmf 2.armature resistance drop 3. brush contact voltage drop Which of these statements is/are correct ?

1 and 3

1, 2 and 3

2 alone

1 and 2

1 and 3

1, 2 and 3

2 alone

1 and 2

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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

1.79 Ω

1.8 9 Ω

3.1 Ω

2 .1 Ω

1.79 Ω

1.8 9 Ω

3.1 Ω

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Electrical Machines
If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

Ph will increase but Pe will decrease

Pe will increase but Ph will decrease

both hysteresis loss(Ph) and eddy current loss(Pe) will increase

Ph will decrease but Pe will remain same

Ph will increase but Pe will decrease

Pe will increase but Ph will decrease

both hysteresis loss(Ph) and eddy current loss(Pe) will increase

Ph will decrease but Pe will remain same

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Electrical Machines
To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

increasing field excitation.

fixing the brush axis inline with the pole axis.

compensating winding and commutating poles.

shifting the brush axis from GNA to MNA.

increasing field excitation.

fixing the brush axis inline with the pole axis.

compensating winding and commutating poles.

shifting the brush axis from GNA to MNA.

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Electrical Machines
In a star - delta starting of an IM

line voltage is 57.7 % of stator voltage.

resistance is inserted in the rotor.

reduced voltage is applied to the stator.

applied voltage per stator phase is 57.7 % of a line volt

line voltage is 57.7 % of stator voltage.

resistance is inserted in the rotor.

reduced voltage is applied to the stator.

applied voltage per stator phase is 57.7 % of a line volt

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Electrical Machines
In dc machines, the space distribution of air-gap flux density wave at no load is

sinusoidal

rectangular

co- sinusoidal

flat-topped

sinusoidal

rectangular

co- sinusoidal

flat-topped

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Electrical Machines

Electrical Machines Consider the following statements : For a level compounded dc generator to run at constant voltage, the series field mmf must effectively compensate 1. armature reaction mmf 2.armature resistance drop 3. brush contact voltage drop Which of these statements is/are correct ?

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 If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

Electrical Machines To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

Electrical Machines In a star - delta starting of an IM

Electrical Machines In dc machines, the space distribution of air-gap flux density wave at no load is

Electrical Machines
Consider the following statements : For a level compounded dc generator to run at constant voltage, the series field mmf must effectively compensate 1. armature reaction mmf 2.armature resistance drop 3. brush contact voltage drop Which of these statements is/are correct ?

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
If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then

Electrical Machines
To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

Electrical Machines
In a star - delta starting of an IM

Electrical Machines
In dc machines, the space distribution of air-gap flux density wave at no load is