1300 ELSAFE (357 233) int:+61 2 9454 7500 railways@elsafe.com.au

Surge Reduction Filter (SRF)

Heavy-duty Surge Reduction Filters

Elsafe Australia has totally re-engineered and widened its range of rugged, heavy-duty Surge Reduction Filters (SRFs) intended for deployment by Heavy Industry as primary surge protection. They include a combination of high current filtering and surge protection components that have been shown to have extremely low let-through voltages during high current transient testing. Mechanically they have also been independently tested and proven to withstand high vibration environments such as railway trackside installations.

  • Surge clamping and filtering technology
  • Safety of thermal fuses and remote monitoring facilities
  • Complies with the stringent vibration and surge let-through voltage
  • regulations
  • Variety of options and models:
  • Single Phase 32A, 63A, 100A (500x400x210mm)
  • Three Phase 63A, 100A, 160A (760x600x210mm)
  • Mild steel or stainless-steel enclosures
  • 10mm stud terminals or 95mm cage clamp terminals

Surge protection is implemented on the load side by means of 100kA-rated Metal-Oxide Varistors (MOVs) connected in a “delta” configuration covering active-to-neutral, active-to-earth and neutral-to-earth. The MOV’s themselves are separated from the line side by custom-made inductors wound from solid copper. The inductor chokes are connected in series directly between the line and load terminals to ensure good continuance of supply. A capacitor between active and neutral forms a filter to attenuate any unwanted high frequency harmonics. The active-to-neutral and active-to-earth MOVs are protected by a single resettable thermal cut-out whose purpose is to isolate them in the event of a transient above their rated specifications.

A Remote Monitor Board provides a single-pole, double-throw, voltage-free changeover contact for sensing the surge protection status of the SRF through telemetry. Connection may be made to its normally-open, normally-closed and common terminals by means of a 3-pin screw connector mounted on the PCB. These contacts are protected from telemetry line transients by separate MOVs that have a varistor voltage of 470V ±10{4f2d99789eca7395d3b28e4858e7c26c2d0254efb42104db217f36abd17417c5} (300Vac maximum). The monitor also gives a local indication of the surge protection status by means of an external blue LED indicator fitted to the SRF’s door.