Symbol for the high voltage winding comes first, followed by the symbols of windings in diminishing sequence of voltage. Some of the commonly used connections with phase displacement of 0, -300, -180″ and -330° (clock-hour setting 0, 1, 6 and 11). Hardly any power system adopts such a large variety of connections. Based on the windings’ connection, the vector group of the transformer is determined. The three phase transformer windings can be connected several ways. Transformers built to ANSI standards usually do not have the vector group shown on their nameplate and instead a vector diagram is given to show the relationship between the primary and other windings. The 11 indicates the LV winding leads the HV by 30 degrees. For example, a step-up transformer with a delta-connected primary, and star-connected secondary, is not written as ‘dY11’, but ‘Yd11’. As the IEC60076-1 standard has stated, the notation is HV-LV in sequence. The point of confusion is occurring in notation in a step-up transformer. Transformer has a delta connected primary winding ( D) a star connected secondary ( y) with the star point brought out ( n) and a phase shift of 30 deg leading ( 11).
Third Symbol: Phase displacement expressed as the clock hour number (1,6,11). d=Delta, s=Star, z=Interconnected star, n=Neutral. Second Symbol: for Low voltage: Always Small letters. D=Delta, S=Star, Z=Interconnected star, N=Neutral. First Symbol: for High Voltage: Always capital letters. When Pair of Coil of Transformer have same direction than voltage induced in both coil are in same direction from one end to other end. When two coil have opposite winding direction than Voltage induced in both coil are in opposite direction. Additive and substractive polarity of transformer When 3 coils are used in a 3 phase transformer winding a number of options exist. The coil voltages can be in phase or displaced as above with the coils connected in star or delta and, in the case of a star winding, have the star point (neutral) brought out to an external terminal or not. The voltages will either be in-phase or displaced by 180 deg. The phase relationship of the two voltages depends upon which way round the coils are connected. Six Ways to wire Star Winding: Six Ways to wire Star WindingĪn AC voltage applied to a coil will induce a voltage in a second coil where the two are linked by a magnetic path. The coil voltages can be in phase or displaced as above with the coils connected in star or delta and, in the case of a star winding, have the star point (neutral) brought out to an external terminal or not. When 3 coils are used in a 3 phase transformer winding a number of options exist. The voltages will either be in-phase or displaced by 180 degree. The phase relationship of the two voltages depends upon which ways round the coils are connected. When two transformers are connected in parallel, their phase shifts must be identical if not, a short circuit will occur when the transformers are energized.”Īn ac voltage applied to a coil will induce a voltage in a second coil where the two are linked by a magnetic path. This condition is called “ no phase shift.”īut when the primary and secondary windings are connected differently, the secondary voltage waveforms will differ from the corresponding primary voltage waveforms by 30 electrical degrees. It’s important to remember that the secondary voltage waveforms are in phase with the primary waveforms when the primary and secondary windings are connected the same way.
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