The different connections between Dyn11 and Yyn0

Transformer Dyn11 connection: high-voltage side delta, low-voltage side star and neutral line tap, high-voltage and low-voltage have a phase difference of 30 degrees

Transformer Yyn0 connection: high-voltage star, low-voltage star with neutral tap, no phase difference between high voltage and low voltage

Yyn0: means high voltage Y connection, that is, star connection, low voltage is also y connection, the low voltage neutral point is derived, and the phase angle on the high and low voltage side is 0 o'clock above the clock.

Dy11: It means high-voltage D connection, that is, triangular connection, and low-voltage connection is also y-connection. The phase angle on the high and low voltage side is the angle at 11 o'clock above the clock, that is, 30 degrees.

In addition, the following knowledge is added:

There are three connection methods for transformer high and low voltage: star, triangle and zigzag connection. For high-voltage windings, use the symbols Y, D, and Z (uppercase); for medium-voltage and low-voltage windings, use y, d, and z (lowercase). When there is a neutral point, it is expressed by YN, ZN (high-pressure neutral point) and yn, zn (low-voltage neutral point). One of the two windings of the autotransformer with a common part having a lower rated voltage is indicated by the symbol a. Transformers are combined in the order of high voltage, medium voltage, and low voltage winding connections to form the winding connection group. For example: high voltage is Y, low voltage is yn connection, then the winding connection group is Yyn. In addition, the clock method indicates that the phasor relationship between the high and low voltage sides is the connection group.

The three commonly used connection groups have different characteristics:

Y connection: The winding current is equal to the line current, the winding voltage is equal to 1 / √3 of the line voltage, and can be made into graded insulation. In addition, the neutral point leads to ground, which can also be used to achieve four-wire power supply. The main disadvantage of this connection is that there is no loop circuit for the third harmonic current.

D connection: The characteristics of D connection are exactly the opposite of those of Y connection.

Z connection: Z connection has the advantage of Y connection, the number of turns is 15.5% more than Y connection. The cost is greater.