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

2 .1 Ω

1.79 Ω

3.1 Ω

1.8 9 Ω

2 .1 Ω

1.79 Ω

3.1 Ω

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Electrical Machines
If the full load speed of 3-phase, 50Hz induction motor is 950 rpm, what is its half load speed nearly equals to?

940 rpm

950 rpm

975 rpm

1000 rpm

940 rpm

950 rpm

975 rpm

1000 rpm

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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 %.

Any where between 75 % and 90 %.

Less than 50 %

Around 90 %

Around 100 %.

Any where between 75 % and 90 %.

Less than 50 %

Around 90 %

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Electrical Machines
No load saturation characteristics are plotted between

short circuit current and field current

short circuit current and armature current

no load voltage and field current

no load voltage and armature current

short circuit current and field current

short circuit current and armature current

no load voltage and field current

no load voltage and armature current

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Electrical Machines
Unbalance 3 - ÃŽÂ¦ stator currents cause

All of these

vibrations.

heating of rotor.

double frequency currents in the rotor.

All of these

vibrations.

heating of rotor.

double frequency currents in the rotor.

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Electrical Machines
A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to

0.5 p.u

0.75 p.u

0.125 p.u

0.25 p.u

0.5 p.u

0.75 p.u

0.125 p.u

0.25 p.u

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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 If the full load speed of 3-phase, 50Hz induction motor is 950 rpm, what is its half load speed nearly equals to?

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

Electrical Machines No load saturation characteristics are plotted between

Electrical Machines Unbalance 3 - ÃŽÂ¦ stator currents cause

Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to

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 full load speed of 3-phase, 50Hz induction motor is 950 rpm, what is its half load speed nearly equals to?

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

Electrical Machines
No load saturation characteristics are plotted between

Electrical Machines
Unbalance 3 - ÃŽÂ¦ stator currents cause

Electrical Machines
A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to