Simple logic of reactance diagram is that simplified equivalent circuit of power system in which the various components of power system are represented by their reactance.
The reactance diagram can be obtained from impedance diagram if all the resistive components are neglected.
So, from figure each of the component is represented by its reactance.
The series electromagnet is energized by a coil known as current coil which is connected in series with the load so that it carry the load current.
The flux produced by this magnet is proportional to and in phase with the load current.