Commonly used wiring methods of transformers

Transformers are one of the most commonly used equipment in power systems. Their main function is to convert high voltage to low voltage or low voltage to high voltage for power transmission, Power distribution, control and other application fields. When using a transformer, there are many commonly used wiring methods, each with its own characteristics and application scenarios. This article will introduce the common wiring methods of transformers one by one to help everyone better understand and apply transformers.

1. Wiring methods of single-phase transformers

In transformers with only one set of windings on both the high and low voltage sides, there are three commonly used wiring methods:

(1) Common neutral wire connection on both sides

Common neutral wire connection on both sides is one of the most commonly used wiring methods for transformers. Both windings at one end of the power supply are connected to ground, while only one winding at the other end is connected to ground, and the other winding connected to the power supply is used to connect to the load. This connection method can effectively reduce the ground fault rate and reduce the use of insulating materials, but it is easy to generate AC magnetic fields between adjacent phases, so attention must be paid to the impact on the receiver.

(2) One lead wire connection on each side

One lead wire connection on each side is a commonly used wiring method in autotransformers and switching power supplies. Its characteristics It is convenient to regulate the voltage and protect the winding. There is no shared neutral line between the two windings, which can effectively avoid the AC magnetic field between adjacent phases.

(3) Two-winding series connection method

Two-winding series connection method is suitable for occasions where large voltage and current need to be output. It connects the power supply and the load in series, which has the advantages of saving insulation materials, increasing the output voltage, and reducing the input current, but it also has shortcomings such as poor anti-interference ability.

2. Wiring method of three-phase transformer

Three-phase transformer is different from single-phase transformer. The rated voltage on its windings is the same but the phases are different. A certain voltage must be maintained between different phases. phase difference, so the commonly used wiring methods in three-phase transformers are also different. The following are commonly used three-phase transformer wiring methods:

(1) Delta connection method

The delta connection method is one of the commonly used wiring methods in three-phase transformers. Its characteristics are: A three-phase three-wire system is adopted, and the windings are connected according to the ABC phase sequence. This connection method can be applied to three-phase power lines to ensure its normal operation and match the load. In the delta connection, the phase difference between the input voltage and the output voltage is 30 degrees, and the voltage amplitude is 3 times the square root.

(2) Star connection

Star connection, also called Y-connection, is one of the more commonly used wiring methods in three-phase transformers. In the star connection method, one endpoint of three groups of windings of the same level forms the "star point", and the other endpoint corresponds to the three-phase voltage of the AC power supply. The voltage between two adjacent endpoints is 3 times the square root. The star connection method can be applied to three-phase balanced or unbalanced loads, and can also ensure the phase difference and voltage stability of the load voltage.

(3) Four-corner connection

Four-corner connection is a wiring method that is not commonly used in three-phase transformers but is sometimes used. It connects three independent transformers appropriately to form a quadrangular type, that is, the three-phase three-wire system becomes a three-phase four-wire system. The four-corner connection method has the advantages of strong anti-interference ability and high output voltage, and is suitable for applications where high voltage output is required.