The testing principle of the pulse reflection flash tester is as follows

When measuring cable faults, the cable can be regarded as a uniformly distributed transmission line. According to the transmission line (long line) theory, a pulse voltage is applied at one end of the cable, and this pulse is transmitted along the line at a certain speed (determined by the dielectric constant and magnetic conductivity of the cable medium). When the pulse encounters the fault point (or impedance non-uniform point), it will reflect. Use a flash meter to record the transmission time △ T between the transmitted pulse and the reflected pulse, The distance Lx to the fault point can be calculated based on the known transmission speed V, where Lx=V · △ T/2
To measure the total length, the terminal reflection pulse can be used: L=V · T/2
The full length of the cable is also known, and the pulse transmission speed can be measured: V=2L/T
Pulse method testing is divided into low voltage pulse method and high voltage pulse method. The testing principle of the two methods is the same, but the method of generating pulses is different. The fault distance calculation of intelligent testers is automatically completed by the instrument.