ZigZag Transformer Connection Overview

Under normal system operation the outer and inner coil winding’s magnetic flux will cancel each other and only negligible current will flow in the in the neutral of the zigzag transformer. During a phase to ground fault the zig-zag transformer’s coils magnetic flux are no longer equal in the faulted line. This allows zero sequence.

In zig zag transformer connection, there are three windings on each of the three limbs of the core, one for primary and two for secondary. Both the windings of secondary are of equal turns. The windings A1A2, a1a2 and a3a4 are wound on the same limb of the core hence they are all colored ‘red’.

A zigzag transformer is a special-purpose transformer with a zigzag or "interconnected star" winding connection, such that each output is the vector sum of two (2) phases offset by 120°. It is used as a grounding transformer, creating a missing neutral connection from an ungrounded 3-phase system to permit the grounding of that neutral to an earth reference point; to perform harmonic ...

Each leg of a grounding transformer carries one-third of the neutral current and has line-to-neutral voltage.So in a grounded wye – delta transformer, the total power rating including all three phases is the neutral current times the line-to-ground voltage:. S = V LG × I N. A zig-zag transformer is more efficient than a grounded wye–delta transformer.

Zigzag transformer has six coils in which three are outer coils and three are inner coils. Outer winding has known as Zig winding and inner winding has known as a zag winding. The zig winding of one phase is connected in series with the zag winding of another phase so it is called interconnected star winding.

The zigzag transformer is a special type of 3 phase transformer. It is used to create a ground for the floating system and also to filter 3rd harmonics in 3 phase AC power supply system.

The cost of zig zag transformer is less than that of scott transformer and star – delta transformer. The application of delta – zig zag transformer is similar to that of star – star and delta – delta transformer because there is not phase shift between primary and secondary winding.

The most common connection used in grounding transformers is the Zig-Zag connection. The grounding transformer is commonly referred to by this connection type, the Zigzag Transformer. Grounding Transformers are used for obtaining a grounded neutral on three phase, three-wire systems, providing a return path for zero sequence current generated by the loads in the system or by the fault currents ...

the zig-zag transformer’s neutral. To specify a zig-zag transformer the following information should be considered: Provide the line to line voltage of the system. Provide the magnitude of the neutral current. Provide how long the neutral current will flow. Typically ten or sixty seconds is used. Provide the System impedance per phase.