The specifics of the star connection and delta connection for electric motors

Assume your input power supply is three-phase 380V AC. If the phase voltage of your motor’s windings is 220V AC, you should use a star connection; if the phase voltage of the motor’s windings is 380V AC, then you should use a delta connection. To reduce the starting current in a delta connection, a star-delta conversion can be used, but this is not possible with a star connection.

The industrial and civil design manual provides very detailed explanations~~

Here is a detailed PLC-controlled star-delta motor circuit diagram for you. http://hi.baidu.com/jl881984/blog/item/9743f6beb587db0d19d81f4e.html

Determine whether to connect in star or delta based on the voltage of the motor’s single-phase winding.

The windings of three-phase asynchronous motors are usually connected in two ways: star connection (Y) and delta connection (Δ). In motors with high power, two or more branches are connected in parallel within each phase winding. In the star connection, the ends of the three-phase set are connected together, while the three ends are connected to the power source. Of course, it is also possible to connect the three terminals together, with the three other terminals being used to connect to the power supply. However, it is absolutely not allowed to have both a start end and an end end at the shorted star point; otherwise, a normal rotating magnetic field cannot be generated. In the junction box, the star point is connected using two connecting pieces. In the triangular connection, one end of a winding is connected to the other end of another winding, forming a triangle; the vertices of this triangle are then connected to the power source. By the same logic, when using a triangular connection, it is absolutely not permissible to connect the like-named ends of the windings (the two ends or the two tails) to form the vertices of the triangle; otherwise, the motor will not operate properly.

The way the motor is connected depends on its rated voltage and the voltage of the three-phase circuit: if the motor’s rated voltage is 380V, and the phase voltage of the three-phase AC supply is 220V (used for lighting), then a delta connection is used; this allows the motor to operate properly since the line voltage becomes 220*1.732=380V. If the phase voltage of the three-phase AC supply is 380V (used for power applications), then a star connection is employed. This is why the motor nameplate has the marking “220/Δ 380/Y”.