core of the signal source should be connected to the cable sheath, and the output of
the cable ground connected to the output of the system ground. It is equivalent to use
the entire cable as the radiating antenna, which greatly enhances the ground radiating
of the cable and it can detect very far of cable path.
It is worth noting that the radiation enhancement of the cable makes the cable
nearby sensitive to the path signal, which may lead to finding other cables instead.
The solution is: 1, Appropriate to reduce the output power of path signal; 2, Back to
find the path from the end of the cable.;3, Use the peak method(observe the amplitude
of the instrument). Make the magnet coil axis parallel to the ground and perpendicular
to the the cable, and slowly move the coil. When the coil is located directly above the
wire and perpendicular to the cable, the magnetic field lines are perpendicular to the
plane of the coil. All the magnetic field lines go through the coil, so the induced
electromotive force generates in the coil, and you can hear the loudest sound in
headphones. Then move the ferrite antenna on both sides. A small part of the magnetic
field lines on both sides will pass through the coil, generating very little induced
electromotive force, so that you can hear very little audio sound in the headphones.
With the slow movement of magnetic antenna, the sound gradually becomes small.
Thus, this effectively avoids the interference induced radiation signal from the rest of
the cable. No wrong path.
4. Locate (Precisely locate method)
In the long-term practice, it has been found that when input a surge voltage with
enough amplitude to the faulty cable, it generates flashover discharge on the point of
fault, at the mean time it also generates considerable "pop, pop" discharge sound,
which can be transmitted to the ground surface. Using this phenomenon to locate can
very accurately locate the fault point without any errors. Method to generate impulse
voltage is quite the same as the method to generate impulse voltage using impulse
flashover method, just remove the distance test equipment; other faults are connected
