Impulse Current Method
The surge generator ignites an arc at the fault which creates a travelling wave between the fault and the surge generator. The TDR Teleflex displays this transient wave which indicates the distance to the fault.
A linear coupler for the impulse current method is installed in all surge generators with an output energy of 1000 J or more.
This method can be useful for all high resitance faults, on wet cables and splices as well as on long paper-lead cables.
ARM Arc Reflection Method
High resistive faults and intermittent faults can easily be located with the ARM Method. If the fault resistance is too high for direct measurement with a TDR Teleflex, a surge generator provides a low resistance arc at the fault which is then clearly located by the Teleflex like a low resistance fault via an ARM Filter. The Teleflex shows a comparison of the traces with and without the arc. It is an easy, clear and precise method and therefore the most commonly used fault locating procedure today and even often replaces burning (fault conditioning) on cables at all.
ARM Filters are also available as separate instruments. Available are passive filters M 219 (inductive) and LSG 300 (resistive). An active Arc Reflection Filter LSG 3-E provides an extra 2 kV power supply and capacitor.
The SPG 32-series features a built-in LSG 300 filter.
For a precise location of the fault it is essential to confirm its position along the cable after prelocation with TDR measurement or any HV-fault locating methods.
All SebaKMT surge generators have a time controlled surge output. It allows a periodical discharge into the cable for acoustic locating of the flash-over at the fault with an adequate ground microphone and receiver.
Combined Acoustic and Magnetic Method
The Digiphone measures the time difference between the magnetic signal of the surge current and the slower acoustic sound of the flash-over travelling through the ground.
The display shows the time delay as indication of fault distance and the magnetic field strength as indication of the cable position.
This means that a low number showing a short time delay indicates a short distance to the fault. This will also work in noisy environment, cable ducts and for faults under paved surfaces.