What is ZigZag Grounding Transformer?

A zig-zag transformer is utilized to provide grounding for the transformer, It provides insulation across the ground & the component, ensuring that the system component is not impacted by fault currents, The grounding transformer creates an artificial neutral point for connecting the grounding resistor. In the event of a grounding fault within the system, it presents high impedance to positive and negative sequence currents while offering low impedance to zero sequence currents. This characteristic ensures reliable operation of the grounding protection system.

Design capabilities

Working of ZigZag Grounding Transformer

Under normal operating conditions, the total flux in each limb is minimal, resulting in the transformer drawing a low magnetizing current. However, during fault conditions, the grounding transformer exhibits very low impedance.To limit the fault current, a resistor can be placed in series with the neutral grounding. This resistor is designed for short-term use and can handle the rated current for up to 10 seconds. A zigzag transformer with a solidly grounded neutral is a suitable option, particularly when high impedance is needed, as its design provides greater impedance.

ZigZag Grounding Transformer Type

[Oil Type]

[Dry Type]

ZigZag Grounding Transformer​ structure

Zig Zag transformer has six coils in which three are outer coils and three are inner coils. The outer coil windings are called as ZIG winding and inner coil windings are connected as 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 where two star winding coils are interconnected each other. In each phase two coil windings will have same number of turns but they are wounded in opposite directions to cancel the mismatch voltages.

Advantages Of ZigZag Grounding Transformer​

• In ungrounded systems, Zig-Zag transformers create a neutral point for steady grounding and safer operation.
• In systems with nonlinear loads, they reduce triplen harmonic currents, enhancing power quality.
• Zig-Zag transformers are cheaper than other grounding transformers due to their simpler design & smaller size.
• The Zig-Zag transformer can balance imbalanced loads across phases, decreasing equipment strain and improving system performance.
• Controlled zero-sequence current paths limit fault current in line-to-ground faults, enhancing safety.
• Their compact and efficient design makes them perfect for space-constrained installations.
• Zig-Zag transformers are more reliable and require less maintenance due to their simpler design and fewer windings.
• They can be used for industrial power distribution, grounding, & neutral formation in low- and medium-voltage systems.
• Zig-Zag transformers may offer neutral grounding without a load, increasing its versatility.
• They lower zero-sequence impedance, minimizing voltage drops during unbalanced load conditions.

ZigZag Grounding Transformer​ applications

Zig Zag transformers are essential grounding transformers in power systems, offering a dependable path for zero-sequence currents

during unbalanced conditions or fault situations. By diverting these currents from the primary windings, Zig Zag transformers contribute

to system stability and equipment protection, safeguarding both the power infrastructure and personnel.

More ZigZag Grounding Transformer​

WINLEY Eletric have been focusing on the transformer field for more than 17 years, with more than 20 independent research and development patents, and have obtained many authoritative certifications such as UL/cUL, CE, ECM, ISO, etc. We have the production capacity of various transformers below 110kv, mainly including pad mounted transformers, pole mounted transformers, cast resin transformers, etc.