For the three-phase motor, the stator winding has two kinds of connection, triangle and star, star connection is to connect the tail of the three-phase winding together, and the head of the three-phase winding is connected with the power supply; The star connection method has two cases of alien connection and internal connection, the internal star connection motor is the star point connected with the three-phase winding is fixed in the appropriate part of the stator winding, there are three outlet ends leading out, and the alien connection is the head and tail of the three-phase winding are all led out, and the external connection and wiring of the motor.
The triangular connection method is to connect the head of a phase winding with the tail of another phase winding, that is, U1 and W2, V1 and U2, W1 and V2, and the connection point is connected to the power supply.
If each phase winding is regarded as a line, after the stars are connected, it resembles a shining star, and the triangle connection law resembles a triangle, so it is called the star connection or triangle connection. We can also connect the triangular motor into two cases of internal Angle and external Angle.
If it is a single-voltage motor, both internal and external can be connected, but for a dual-voltage motor, only the head and tail of the three-phase winding can be drawn out, and then the external connection is carried out according to the voltage situation, and the high voltage corresponds to the star connection and the low voltage corresponds to the Angle connection.
Why use star connection for high voltage motors：
For low-voltage motors, it will be segmented according to the power, such as the basic series of motors according to 3kW division, not more than 3kW according to the star connection, the other according to the Angle connection, and for variable frequency motors, it is according to 45kW division, not more than 45kW according to the star connection, the other according to the Angle connection; For lifting and metallurgical motors, there are more star joints, and large size lifting motors will also use Angle joints.The high voltage motor is generally a star connection mode, the purpose is to avoid the motor winding to withstand high voltage. In the star connection, the line current is equal to the phase current, and the line voltage is 3 times the root of the phase voltage (in the triangle connection, the line voltage is equal to the phase voltage and the line current is equal to the √3 times of the phase current), so the voltage borne by the motor winding is relatively low. In high-voltage motors, the current is often small, and the insulation level of the motor is higher, so the insulation of the star connection motor is better treated and more economical.
Post time: May-29-2024
