I am studying the behavior of the magnetic fields between the rotor field and stator field(armature reaction) in a synchronous generator . I understand that the stator magnetic flux will vary depending on the power factor of the load (leading, lagging or resistive). If the load is resistive, the magnetic field of the stator will be at 90 degrees of separation, while the load is lagging(inductor) the magnetic field will be 180 degree respect the rotor field and finally, if the load is leading(capacitor) the magnetic field will be zero degree respect the rotor field. Ok, this part I am clear but when I am reading the definition of "Load Angle", it's said that is the angle between the rotor field and stator field and the maximum degree of separation is 90 . If I think in the behavior of the magnetic field before mentioned ,I saw that I can to have until 180 degree of separation. Can someone explain me this to me with images or easy way to see? . Furthermore, at generator Capability curves one can appreciate the load angle is 90 degrees when in the area of UNDER EXCITATION (leading area). I cant see How the load angle sets the stabilization limit of the machine when in a leading load the magnetic field of the stator is en the same axis of the rotor field.