stator field and rotor field strengths and the torque angle
Torque developed in an electromechanical energy conversion device depends upon stator field and rotor field strengths and the torque angle.
permit mechanical clearance
In electromechanical energy conversion devices (e.g generators and motors) a small air gap is left between the stator and the rotor in order to permit mechanical clearance.
the net force and torque on the coil are both zero
If a current carrying coil is placed in a uniform magnetic field direction of magnetic induction, then the net force and torque on the coil are both zero.
reluctance seen by the working mmf varies
Reluctance torque in rotating machines is present, when reluctance seen by the working mmf varies.
The emf induced in a conductor rotating in a bipolar field is AC
Along the axis of the magnetic field
A conductor is rotating within a magnetic field. Peak voltages occur when the conductor is Along the axis of the magnetic field.
Rate of change of flux linkage is maximum
EMF induced ina coil rotating in a uniform magnetic field will be maximum when the Rate of change of flux linkage is maximum.
Square of the armature speed
In a dc motor the windage loss is proportional to Square of the armature speed.
Copper loss and stray load loss
Copper loss and stray load losses are the variable losses in a rotating machine.
Iron and mechanical losses
Stray losses are sum of Iron and mechanical losses.
Parallel resistance with a high value
Generally, the no – load losses of an electrical machine is represented in its equivalent circuit by Parallel resistance with a high value.
The principle of dynamically induced emf is utilized in Generator.
The current and emf in armature conductors are alternating while those at the terminals are unidirectional
The field coils of a dc generator are usually made of Copper because it has good electrical conductivity as well as good thermal conductivity.
Laminated yoke in dc motor can reduce Iron loss.
Decreasing eddy current loss
Pole shoe of a dc machine is laminated for the purpose of Decreasing eddy current loss.
All of the above
The function of pole shoes in a dc machine is to Support the field coils, Reduce the reluctance of the magnetic path, Spread out the flux to achieve uniform flux distribution in the air gap.
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