The technique of Arc Reflection (ARC) combines the surge wave generator (thumper) and the pulse echo technique (TDR) for the purpose of locating high resistance shunt faults and intermittent shunt faults. fault position. Note: This method is extremely effective and the traces are easy to interpret. Differential Arc Reflection Technique (DART) equipment as previous. To overcome this limitation of TDR, following are some popular high voltage radar methods. (i) Arc reflection method, (ii) surge pulse reflection method and (iii).


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Locating Underground Cable Faults

The higher the dc voltage applied, the louder arc reflection method be the resulting thump. This method is useful for relatively shorter cables. For longer cables, the thumping method becomes impracticable imagine walking along a cable that runs several kilometers to hear the thump.

Advantages and disadvantages of cable thumping A major advantage of cable thumping is that it can locate open circuit faults very accurately. Also, this method is easy to apply as well as easy to learn. Though the thumping method provides very accurate fault location, it has its own arc reflection method.

  • Arc Reflection Technique (ARC) for Cable Fault Locating - KEP Power Testing Blog
  • Time Domain Reflectometer (TDR)

Applying this method for longer cables is extremely time-consuming. It may take hours or even days to walk along the cable to locate the fault. Moreover, during that arc reflection method, the cable is exposed to high voltage surges.

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So while the existing fault is located, the high arc reflection method surges may weaken the insulation of the cable. If you are proficient in cable thumping, you can limit the damage to the cable insulation by reducing the power sent through the cable to the minimum required to conduct the test.

While moderate thumping may not cause noticeable damage, frequent thumping may degrade the cable insulation to an unacceptable condition. Also, this technique can not find faults that do not arc-over i. Arc reflection method signal reflects back from the point of change in impedance in the cable such as a fault.

A TDR measures the time taken by the signal to reflect back from the point of change in impedance or the point of fault. The reflections are traced on a graphical display with amplitude on y-axis and the elapsed time on x-axis.


The elapsed time is directly related to the distance to the fault location. If the injected signal encounters an open circuit high impedanceit results in high amplitude upward deflection on the trace.

While in case of a short-circuit fault, the trace arc reflection method show a high amplitude negative deflection.

Signal transmitted through and reflected back from a fault Advantages and disadvantages of TDR As a TDR sends a arc reflection method energy signal into the cable, it causes no degradation of the cable insulation. This is a major advantage of using TDR arc reflection method find the location of a fault in an underground cable.

A TDR works well for open-circuit faults as well as conductor to conductor shorts.

Locating Underground Cable Faults |

A weakness of TDR is that it cannot pinpoint the exact location of faults. It gives an approximate distance to the location of fault. Sometimes, this information alone is arc reflection method and other times it only serves to allow more precise thumping.


Due to the reflection characteristics of these high resistance faults they are impossible to see using only the low voltage TDR.

Arc Reflection Method The arc reflection method reflection method of fault prelocating combines the use of a TDR cable radar and a surge generator thumper.

Underground Cable Fault Locating Using the Arc Reflection Method

By using an arc reflection filter, a low voltage TDR and a high voltage surge generator can both be connected to the faulted cable and the TDR can be looking down the cable while thumping. The filter protects the TDR from the surge generator high voltage pulses and routes arc reflection method low voltage pulses down the cable.

This method utilizes the fact that when an arc is created at the fault, its resistance is reduced to a very low value, less than ohms, which will reflect radar pulses. The arc location will appear as a downward going reflection on the TDR cable trace.


The cable analysis systems should capture and store the complete trace including the downward going fault location in memory so measurements can be made easily.

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