Cable Fault Locater

A Thumper and Burner are almost the same from what I remember from my days as an apprentice both can be used with impulse reflection.

My one experience of using a thumper made finding an 11KV cable fault easy. The faulty cable joint caught fire! We were going to use impulse reflection after using the thumper but there wasn't much point when there's smoke pouring out of a joint. We could see it ½ a mile away.

Which impulse reflection that you used after thumping, Secondary impulse or current impulse?

Is there any advantage for one over another?

From what I remember (it was over 30 years ago) it would have been a form of secondary impulse. We tried it before using the thumper and it didn't show a clear fault. We were reluctant to use the thumper because of the damage they can cause, the cable had been installed in the 1920's. There were many joints in the cable each of which gives a reflection, so the faulty joint just showed as a joint. Setting fire to it didn't need a reflection. Somewhere I've got the results of the first test in my training log, but I don't know where they are at the moment.

I think secondary impulse is using for problems like earth fault, cable to cable short etc. Impulse current is using for problems like open circuit (High impedance). Is it correct?

If we do comparison of secondary current impulse method with thumping method, which method is more effective?

Thumping requires a current on the order of tens of thousands of amps at voltages as high as 25kV to make an underground noise loud enough for you to hear above ground.The heating from this high current often causes some degradation of the cable insulation.

The SIM/MIM is the latest and most efficient measuring method for pre-locating cable faults. The benefits of this method is the simple handling, universal application and extremely simple interpretation of the echograms.

I got the answer............

http://www.electrotest.co.nz/PDF/ETLCableFaultLocation04-09.pdf