φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

960 RPM

920 RPM

970 RPM

940 RPM

960 RPM

920 RPM

970 RPM

940 RPM

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Electrical Machines
In a 3 - ÃŽÂ¦ IM with line frequency f1 and winding factor kw1 and kw2 for stator and rotor respectively the ratio of per phase stator winding emf E1 to per phase rotor winding emf E2 at standstill is given by

E1 / E2 = N1kw1 / N2kw2.

E1 / E2 = N1 / N2.

E1 / E2 = 1.

E1 / E2 = f1kw1 / f2kw2.

E1 / E2 = N1kw1 / N2kw2.

E1 / E2 = N1 / N2.

E1 / E2 = 1.

E1 / E2 = f1kw1 / f2kw2.

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Electrical Machines
The damper windings also called the squirrel cage windings or damper grids

both (A) and (B).

are provided on the stator for improving power factor.

consists of short-circuited copper bars embedded in the field pole faces.

are provided in a synchronous motor to make it self starting.

both (A) and (B).

are provided on the stator for improving power factor.

consists of short-circuited copper bars embedded in the field pole faces.

are provided in a synchronous motor to make it self starting.

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Electrical Machines
In which of the following generators negative voltage regulation can occur?

both B and C

over compound generator

shunt generator

series generators

both B and C

over compound generator

shunt generator

series generators

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Electrical Machines
What is the phase difference between two windings of A.C servomotor ?

60°.

90°.

30°.

120°.

60°.

90°.

30°.

120°.

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Electrical Machines
Belt conveyors offer _______________ starting torque.

low.

medium.

high.

zero.

low.

medium.

high.

zero.

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Electrical Machines

Electrical Machines φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines In a 3 - ÃŽÂ¦ IM with line frequency f1 and winding factor kw1 and kw2 for stator and rotor respectively the ratio of per phase stator winding emf E1 to per phase rotor winding emf E2 at standstill is given by

Electrical Machines The damper windings also called the squirrel cage windings or damper grids

Electrical Machines In which of the following generators negative voltage regulation can occur?

Electrical Machines What is the phase difference between two windings of A.C servomotor ?

Electrical Machines Belt conveyors offer _______________ starting torque.

Electrical Machines
φA DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the speed when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%.

Electrical Machines
In a 3 - ÃŽÂ¦ IM with line frequency f1 and winding factor kw1 and kw2 for stator and rotor respectively the ratio of per phase stator winding emf E1 to per phase rotor winding emf E2 at standstill is given by

Electrical Machines
The damper windings also called the squirrel cage windings or damper grids

Electrical Machines
In which of the following generators negative voltage regulation can occur?

Electrical Machines
What is the phase difference between two windings of A.C servomotor ?

Electrical Machines
Belt conveyors offer _______________ starting torque.