Earth Fault Protection System
Arc Suppression Coils

Single-phase neutral earthing (grounding) reactors (Arc Suppression Coils) are intended to compensate for the capacitive line-to-earth current during a 1-phase earth fault. The arc-suppression coil (ASC) represents the central element of the Trench earth-fault protection system.

Because the electric system is subject to changes, the inductance of the ASC used for neutral earthing must be variable. The earth-fault detection system develped by Trench utilizes the plunger core oil (moveable-core design). Based on extensive experience in design, construction and application of ASCs, Trench products can meet the most stringent requirement for earth-fault compensating techniques.

Resonant grounded systems suppress transient ground faults and enable to continue power supply even during single pole earth faults.

For special requirements neutral point coupler (earthing transformer) and stepless adjustable ASC can be housed in a common tank forming a so called Neutral Earthing Aggregate.


  • Up to power ratings of 35 MVAr
  • Up to system voltage of 145 kV
  • Current regulation range 10 - 100 %
  • Various design alternatives are available


Arc Suppression Coils