The earthing transformer used in compensated system is often combined with an arc-suppression- or limiting reactor in order to provide an appropriate reactance and clearing of earth currents & arc. In isolated neutral system the earthing transformer is often used together with resistors.

By designing this type of transformer the Manufacturer has to consider extremely low ground impedance, ensuring at the same time the correct short circuit voltage on the auxiliary winding. Each of three limbs of earthing transformer consists of two different winding segments connected differentially. In order to generate a common neutral junction, all phase terminals are joint by a single connection.

Zig-zag connection scheme

 Zig-zag connection on transformer


The most popular vectorial group required by this kind of transformer is Zig-Zag connection or better an inter-connected star connection. This type of arrangement has to guarantee special features:

  • generation of stable neutral point
  • absence of harmonic contents
  • providing very low impedance for the zero sequence currents
  • no influence of the current fault on the secondary side
  • no electric stress on winding insulation

Neutral grounding transformers, produced by Power are available for short-time operation or continuous operation. The offered power range goes from 10 kVA up to 5 MVA.

For further technical questions please get in touch with our office at

Stay tunned at

Your Power Team