The Directional Impulse Detector ( D.I.D.) is a compact handheld detector used to locate primary cable faults by sensing the magnetic field generated by the current pulse from a high voltage discharge device (thumper). A meter deflection indicates the intensity of the received signal. No deflection indicates that you have walked beyond the fault or away from the cable. The high sensitivity of the DID reduces stresses to the cable by locating the fault while thumping at the minimum voltage required to flashover at the fault.