Vector Groups

Mehran University College
Of Engineering & Technology,
Khairpur Mir’s

VECTOR GROUPS

ENGR. AHSANULLAH MEMON
LECTURER
DEPARTMENT OF ELECTRICAL ENGINEERING MUCET KHAIRPUR MIRS

ZIGZAG CONNECTION OF TRANSFORMER
 The zigzag connection of tranformer is also called the interconnected star connection.
 This connection has some of the features of the Y and the ∆ connections, combining the advantages of both.
 The zigzag transformer contains six coils on three cores.  Its applications are for the deviation of a neutral connection from an ungrounded 3-phase system and the grounding of that neutral to an earth reference point and harmonics mitigation.
 It can cancel triplet (3rd, 9th, 15th, 21st, etc.) harmonic currents.

INTRODUCTION
 Secondary voltage waveforms are in phase with the primary waveforms.
 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.”
 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.”

Vector Group of Transformer
 The three phase transformer windings can be connected several ways. Based on the windings’ connection, the vector group of the transformer is determined.
 The transformer vector group is indicated on the Name Plate of transformer by the manufacturer.
 The vector group indicates the phase difference between the primary and secondary sides, introduced due to that particular configuration of transformer windings connection.
 The Determination of vector group of transformers is very important before connecting two or more transformers in parallel.  If two transformers of different vector groups are connected in parallel then phase difference exist between the secondary of the transformers and large circulating current flows between the two transformers which is very detrimental.

 The digits (0, 1, 11 etc) relate