How many ways are there to connect a three-phase power supply? What are they?

There are three types of connections for a three-phase power supply: star, delta, and hybrid star-delta. The following is a detailed description of these three types of connections.

Star Connection

Star connection is one of the most common types of three-phase power connections. In a star connection, each phase wire is connected to a common neutral wire, forming a star pattern centered on the neutral wire. This type of connection is commonly used for low-power equipment and household power. In a star connection, the relationship between line voltage (U) and phase voltage (U phase) is a root 3 times relationship, i.e. U = √3 * U phase. The relationship between line current (I) and phase current (I phase) is equal.

Triangular Connection

Triangular connection is another common way of connecting a three-phase power supply. In a triangular connection, each phase wire is directly connected to the neighboring phase wires to form a closed triangle pattern. This type of connection is commonly used for high power equipment and industrial power. In a triangular connection, the relationship between the line current (I) and the phase currents (I phase) is a root 3 times relationship, i.e. I = √3 * I phase. The relationship between line voltage (U) and phase voltage (U phase) is equal.

Star-Delta Hybrid Connection

A star-delta hybrid connection is a type of connection that combines a star connection with a delta connection. In a star-delta hybrid connection, one side of the three-phase power supply is connected by a star connection and the other side by a delta connection. This type of connection is often used for special industrial applications where both low and high power equipment can be accommodated. The advantage of the hybrid star-delta connection is that it reduces the short-circuit current and current harmonics of the power supply, improving the reliability and stability of the system.

To summarize, star connections are used for low-power devices and household power, delta connections are used for high-power devices and industrial power, and hybrid star-delta connections are a special type of connection used to meet the needs of specific industrial applications. Regardless of which connection method is used, it is necessary to select the appropriate connection method according to the specific electrical requirements and equipment characteristics to ensure the stable operation of the power system.