The diagram shows three arrangements of a metadyne machine. In all cases, compensation windings have been omitted for clarity. The first arrangement represents a one-cycle cross-field machine. In a normal DC machine, the effect of the excitation current generates a flux (A1), which in turn generates a quadrature flux which is at right angles to the exciting flux. By wiring the quadrature brushes together, current is produced in the armature, and the flux that this produces (A2) is again at right angles to the quadrature axis, resulting in an armature reaction which is directly opposed to the original excitation. This feature is fundamental to the machine, and does not depend on its direction of rotation. When the armature reaction is partially compensated by a compensation winding, the uncompensated portion of the armature reaction acts in this way. As the output current rises, it suppresses the effect of the excitation, until it reaches a state where there is just enough excitation to maintain the current. Any further increase would eliminate the flux which sustains its operation, and the current is maintained irrespective of the resistance of the load or the back emf produced by it. The machine thus acts as a constant-current generator, where the current is proportional to the excitation.