The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

Electrical Machines
The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

48.0%.

88.8%.

57.1%.

59.2%.

48.0%.

88.8%.

57.1%.

59.2%.

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Electrical Machines
Which of the following represents the pitch factor?

Cos α²

Cos α

sin (α/2)

Cos (α/2)

Cos α²

Cos α

sin (α/2)

Cos (α/2)

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

are provided on the stator for improving power factor.

both (A) and (B).

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

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

are provided on the stator for improving power factor.

both (A) and (B).

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
Which DC motor will have least percentage increase of input current, for the same percentage increase in the torque

DC Shunt Motor

DC Series Motor

Separately Excited DC Motor

Compound Wound DC Motor

DC Shunt Motor

DC Series Motor

Separately Excited DC Motor

Compound Wound DC Motor

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Electrical Machines
In DC machine torque is proportional to which of the following?

armature current(Ia)

None of these

flux(φ)

both A and B

armature current(Ia)

None of these

flux(φ)

both A and B

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Electrical Machines
What type of connection is made in between the inter-pole and the field winding?

Compound.

None of the options.

Series.

Parallel.

Compound.

None of the options.

Series.

Parallel.

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Electrical Machines

Electrical Machines The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

Electrical Machines Which of the following represents the pitch factor?

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

Electrical Machines Which DC motor will have least percentage increase of input current, for the same percentage increase in the torque

Electrical Machines In DC machine torque is proportional to which of the following?

Electrical Machines What type of connection is made in between the inter-pole and the field winding?

Electrical Machines
The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be

Electrical Machines
Which of the following represents the pitch factor?

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

Electrical Machines
Which DC motor will have least percentage increase of input current, for the same percentage increase in the torque

Electrical Machines
In DC machine torque is proportional to which of the following?

Electrical Machines
What type of connection is made in between the inter-pole and the field winding?