We use a BAUA surge generator STA 1100 or thumper.
This method is used to locate faults within an armoured cable or for faults between phase to phase and phase to screen.
We use a Biddle stereo microphone, and magnetometer set for pinpointing the fault.
It pays, prior to thumping to mark out the cable route with a Radiodetection or other cable locator. especially in noisy areas.
Accuracy is within one meter of the fault.
For ground faults in single core cables we use the POPIE ( pool of potential in earth ) method.
This is basically a pulsing HV dc supply, which is short circuit proof.
A testcurrent of about 60 mA is enough to pinpoint the fault within 5 cm. (2 inches)
A balanced µA meter with two probes is used for the pinpointing.
The product of rotation, excitation and flux produces electricty.