Transformer DYN11 connection:High pressure side triangles, low-voltage side stars and neutral lines, high pressure and low pressure have a 30 degree phase difference
Transformer YYN0 connection:High pressure side star, low-voltage side star and neutral line, high pressure and low pressure have no phase difference
YYN0: It means that the high pressure Y is connected, that is, the star is connected, the low pressure is also Y connected, the low pressure neutral point is taken out, and the high and low voltage side phase angle is 0 when the clock is 0.
DY11: It means that high pressure D is connected, that is, the triangular connection, the low pressure is also Y connected, the high and low pressure side phase angle is angle at 11 o’clock in the clock, “11” indicates the line voltage hysteresis on the secondary side of the transformer 330 330 Degree (or advance 30 degrees).
Also add as follows:
There are three ways to connect the transformer high and low pressure: stars, triangles and zibles. The high voltage windings are represented by symbols Y, D, Z (capital); the medium pressure and low voltage windings are represented by Y, D, Z (lowercase), respectively. There is a neutral point to expire with Yn, Zn (high pressure neutral point) and Yn, Zn (low pressure neutral point), respectively.
The digital use clock representation, used to represent the phase relationship of the secondary side voltage, the primary side voltage phase is used as a minute, fixed refers to the position of the clock 12 points, the secondary side line voltage phase amount as a hour hand.
The autotranspurator is represented by a nominal voltage in a common part of the two windings. The transformer is combined in the order of high pressure and low pressure winding linkage is the joint group of the windings.
For example, the high pressure is Y, the low pressure is the YN connection, then the winding group is YYN. Plus the clock method indicates that the high and low voltage side phase is the connection group.
The two windings of the transformer form four wiring groups: “YY”, “DY”, “YD” and “DD”. Due to the Y connection, there are both neutral lines and non-neutral lines, without neutral lines, no symbols are added, with neutral lines to add alphabet n to the letter N. n indicates that the neutral point has an lead line. The YN0 wiring group, UAB is in combination with UAB, and when the division refers to 12. “12” is represented in the new wiring group.
Commonly used three joint groups different characteristics:
1. Y coupled: Star Wiring is characterized by the most economical windows. The star wiring allows the insulation at the midpoint to reduce the transformer high voltage winding to reduce costs. The star wiring winding voltage is equal to 1 / √3 of the line voltage, the winding current is equal to the line current. The neutral point lead line of the stars can also be used directly, or grounded by an arc-arc, and if it is not grounded, it can be taken away, preventing overvoltage and lightning overvoltage. In addition, neutral points leads to ground, or it can be used to achieve four-wire power supply. The main disadvantage of this linkage is that there is no loop circuit of the three harmonic current.
2. D Counter: The triangular wiring is the most economical transformer low voltage winding for voltage and current. Because the triangular wiring must be made of insulation, it cannot be made to be hierarchical. For low voltage windings, this will not have any effect because the voltage is low. The current in each of the triangular wiring is only 1 / √3 of the lead current. The triangular pick method can circulate the zero sequence current and three harmonic currents in the winding, producing a flat force zero-ranging magnetic flux and the three harmonics, so that the sensing electromotive force of the transformer avoids distortion.
3. Z Joint: The Z Joint has the advantage of Y couples, and the number of turns is 15.5% more than Y-shaped, and the cost is large. Its zero-sequence impedance is small, suitable for manufacturing ground transformers. Since the neutral displacement can be reduced, a small and medium-sized capacity transformer low pressure winding is required to be manufactured to three-phase imbalanced load. In addition, there is a role in preventing lightning overvoltage.
DYN11 and YYN0 Differences Differences:
Due to the high-voltage side of the triangular wiring, when a zero-rader magnetic flux or three harmonic flux occurs in the transformer core, induction zero-sequence electromotive force or three harmonic electromotive force is induced in the triangular winding, since this sensing electromotive force is three identical phase, The triangular windings are superimposed in series and generate corresponding currents. This zero-sequence (three harmonic) circulation current generates an anti-magnetic flux, so that zero sequence (three harmonics) in the core is weak to minimize, thereby reducing the neutral point voltage of low-voltage side star wiring windings. Displacement. At the same time, zero sequence (three harmonics) in the high pressure side winding is also minimized, thereby avoiding pollution due to low pressure side load current waveform distortion caused by high pressure side power grids. Therefore, a transformer having a triangular wiring can prevent the effects of three harmonic or zero-rade magnetic flux on the high voltage side power supply voltage waveform. In addition, this coupling method also has a good role in preventing overvoltage of lightning intrusion. Because the three-phase lightning invasion wave is also in the same direction, this condition is similar to the zero sequence current, the circulation current generated in the triangular windings, the magnetic flux generated in the transformer three-phase iron core is also inhibitively effect.
GB / T13499-2002 “Power Transformer Application Guide” Provisions: Since the zero-sequence impedance of YYN transformer is as high as 60%, the neutral line current should not be greater than 10% of the rated current; the DYN transformer zero-sequence impedance is only 0.9 times the short-range short-circuit impedance The neutral line can be rated with rated current.
However, the DYN11 coupling mode transformer power side is used as overload and short circuit protection, the high pressure side single-phase disconnect line, that is, the high pressure side single-phase disconnect line, and the high pressure side single-phase disrupt line is rated. 1/2 of the voltage, that is, from 220V to 110V, at this time, the household appliances such as the refrigerator will cause burning due to unable to start. At this time, the DYN11 coupled mode of transformers must be installed with reliable low voltage protection.
This connection combination method, low-voltage side having neutral lines, three harmonic currents in low pressure loads and zero sequence currents in the three-phase imbalanced load can be circulated in the transformer winding by neutral lines. If the core is a three-phase three column, the zero-sequence current and the three harmonic current generated in the winding cannot be formed in the core (because the three harmonic current flux in the three-phase iron core column) Zero-rade magnetic flux is in the same direction), which can only go back to the iron core through the iron core essentially by the transformer insulating medium (transformer oil) and the box iron metal. Since the magnetoresformation of the insulating medium outside the core is large, the zero-sequence magnetic flux and the three harmonic flux are small. However, the zero-sequence electromotive force and three harmonic electromotive motion generated by its induction are superimposed on phase voltages, causing the three-phase voltage asymmetrical, causing neutral displacement, and there is a high phase voltage rise, and some phase voltage is lowered. In order to prevent the three-phase voltages from serious asymmetry, affect the normal use of the user, industry standard SD-292-1988 “Overhead distribution line and equipment operation procedure (trial)” to the three-phase load unbalanced level regulations should not be greater than 15% . Allows a small amount of single-phase load in the three-phase transformer, but the neutral line current should not exceed 25% of the rated current. Therefore, this provision is to limit the neutral displacement voltage to about 5%.
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