What is armature reaction explain the effect of armature reaction on synchronous machine at different power factor?

The armature reaction flux is constant in magnitude and rotates at synchronous speed. The armature reaction is cross-magnetizing when the generator supplies a load at unity power factor. When the generator supplies a load, at lagging power, the armature reaction is partly demagnetizing and partly cross-magnetizing.

What is armature mmf in DC machine?

The armature MMF of a distributed armature winding of a dc machine is triangular in shape as shown in fig. In a D.C. machine, the armature M.M.F. wave has its maximum value at fixed points between the main poles.

What is MMF in armature reaction?

This m.m.f. sets up a magnetic flux and the effect of this flux on that set up by the main poles is called armature reaction. The armature m.m.f. is acting on a relatively small airgap under the main poles and on a long air path of high reluctance between the poles. Resultant flux in the air gap of a d.c. machine.

What is the armature MMF in dc machine?

The armature mmf in a dc machine is stationary with respect to field poles but rotating with respect to armature. In case of a deferentially compounded generator with the increase in load current series field flux opposes the main field flux due to which terminal voltage falls rapidly.

What is the effect of armature reaction on performance of synchronous machine?

Due to armature reaction, flux is reduced or distorted, the net emf induced is also affected and hence the performance of the machine degrades.

Why will a 3 phase synchronous motor always run at synchronous speed?

The rotating magnetic field which is produced in the stator will generate flux in the rotor which will make the rotor rotate. But due to the lagging of rotor flux current with respect to stator flux current, the rotor will never reach its rotating magnetic field speed i.e. the synchronous speed.