2Y-△ connection two-speed motor contactor control circuit four

 The circuit is shown in Figure 3-99. This circuit can start the motor at low speed (Δ-shaped connection), and then automatically increase the speed and
put it into high-speed operation (2Y-shaped connection). The interval time from low-speed start to high-speed operation can be adjusted by the time relay KT.
    In the picture, SBi is the low speed start button.