Current relay secondary starting circuit

160. The circuit is shown in Figure 3-160. This circuit uses a current relay to control the resistance value in the rotor winding, changes
the rotor current, and starts the motor in stages.
    In the figure, Ri and Rz are resistors for graded starting. The first-level starting current is detected by the current relay KIl connected in series with Ri , and the second-level starting current is detected by the current relay
KIz connected in series with Ri . Since the first-stage starting current is larger than the second-stage starting current, the release current of KL should be made larger than the release current of KIz during setting. They have the same pull-in current.