How is the transformer connected?

time：2025-03-15 Edit：switchgear view：38

There are mainly the following wiring methods for the transformer, and different wiring methods are applicable

to different application scenarios and power system requirements:

Y - Y (Star - Star) Wiring

-Characteristics: Both the primary and secondary windings are connected in a star shape. The neutral point of this

wiring method can be drawn out or not. If the neutral point is drawn out, it can be used for three-phase four-wire

power supply, which can provide two voltage levels, namely line voltage and phase voltage. It is often used in low-voltage

distribution systems to supply power to a mixed load of power and lighting.

Applications: It is suitable for three-phase circuits with balanced loads, such as large motors. However, when the

three-phase load is unbalanced in this wiring method, the neutral point will be displaced, resulting in asymmetric

phase voltages and affecting the power supply quality.

Y - Δ (Star - Delta) Wiring

Characteristics: The primary winding is connected in a star shape, and the secondary winding is connected in a

delta shape. Using a star connection for the primary side can reduce the insulation requirements of the winding,

and using a delta connection for the secondary side can eliminate the third harmonics and improve the voltage waveform.

Applications: It is often used for step-down transformers. In the power system, it can be used to convert high-voltage

electrical energy into electrical energy suitable for medium-voltage or low-voltage distribution systems.

Δ - Y (Delta - Star) Wiring

Characteristics: Contrary to the Y - Δ wiring, the primary winding is connected in a delta shape, and the secondary

winding is connected in a star shape. This wiring method can increase the output voltage of the transformer, and the

delta connection of the primary side has a good suppression effect on the third harmonics.

- **Applications**: It is often used for step-up transformers to raise the lower voltage generated by the generator

to a voltage level suitable for long-distance power transmission.

Δ - Δ (Delta - Delta) Wiring

Characteristics: Both the primary and secondary windings are connected in a delta shape. In this wiring method,

the winding current is relatively small, the insulation requirements for the winding are relatively low, and it can withstand

large load changes.

Applications: It is suitable for occasions where the three-phase load is balanced and a large capacity is required, such

as the power supply system of large industrial enterprises.

When wiring the transformer, it is necessary to operate strictly in accordance with the nameplate markings of the transformer

and relevant electrical specifications to ensure that the wiring is correct and firm, so as to ensure the safe and reliable operation

of the transformer. At the same time, factors such as the grounding method of the neutral point of the transformer and the

configuration of the protection device also need to be considered to meet the stability and safety requirements of the power system.