A thumper is a capacitor-discharge surge generator that repeatedly dumps a high-voltage pulse, from a few kilovolts up to 32 kV or more, into a faulted underground cable. At the fault the insulation breaks down with an audible thump and ground vibration, which crews pinpoint with an acoustic pickup after a time-domain reflectometer gives an approximate distance. Too much thumping can damage healthy insulation, so energy and the number of shots are kept low.
TDR puts the fault about 340 metres out, set the thumper to 12 kV and walk the route with the ground mic.
Also heard as
- surge generator
- cable thumper
Related terms
Pothead
Field name for the termination where an underground power cable meets an overhead line or equipment.
Earth fault
Fault in which a live conductor makes unintended contact with earth or with earthed metalwork.
Ring out
To check continuity and identity of every core of a cable end to end before termination or after a fault.