ARM Filter in a black rugged case with the lid open, a clear cover over the connection panel, and a mains inlet with a red switch.

Lid open: a clear cover over the connection panel, a mains inlet with switch, and a strap-on pouch.

Step 1 of 4: Pre-location

ARM Filter Arc reflection filter

Joins the reflectometer to the surge generator, so a high-resistance fault can be pre-located while it arcs.

Method: Arc reflection (ARM)
Connects: TDR-901 and a surge generator
For: High-resistance and intermittent faults
Power: Mains inlet with switch

Where it fits

The ARM Filter belongs to step 1, but it works only together with step 2: it joins the reflectometer to the surge generator.

1
Step 1: Pre-locate
You are here
- TDR-901 Time domain reflectometer
- ARM Filter Arc reflection filter
2
Step 2: Condition
- PG-10 Surge generator, 10 kV
- PG-32 Surge generator, 30 kV
3
Step 3: Pinpoint
- AP-01 Acoustic pinpointer
4
Step 4: Trace route
- CRT-015 Cable route tracer

What arc reflection does

The method in plain words, and where the ARM Filter sits.

A reflectometer sees open circuits and short circuits clearly. Many real faults are neither: a high-resistance fault reflects almost nothing, so the trace looks like a healthy cable.

Low-voltage shot only. The pulse runs past the fault and reflects from the far end.

Shot during the arc. The surge makes the fault arc over. For that moment it is a short circuit, and the pulse reflects sharply from it.

The surge generator fires into the cable and the fault flashes over. A pulse sent while it arcs comes back from the fault, not from the far end. Lay the two traces over each other and they part at the fault distance.

The ARM Filter makes that timing possible. It joins the TDR-901 to the surge circuit, protecting the reflectometer from the surge while letting its pulse onto the cable.