NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
Author: Noyafa–Noyafa Cable Tester
How to use the cable fault distance meter How to use the cable fault distance meter Measure the distance In fact, it is related to the radar or echo principle that we all know how to use the cable fault distance meter to measure the distance. The cable fault ammeter measures the distance to the cable fault. In fact, it is similar to the radar or echo principle we all know.
We all know that sound bounces when hitting an obstacle, that's why we hear the echo. A low-voltage pulse is an electrical signal (wave) in a cable. After encountering the fault point, the electric wave will reflect the echo.
The reason why the echo can be reflected at the fault point of the cable is that the impedance of the normal cable on the theoretical line is uniform, and it can also be understood that the molecular structure on the line is uniform. It's like radar detecting planes. Empty skies have no radar echoes, so radar can't show planes.
Only when the plane is in the air, as the impedance at that point of the plane has changed, will the reflected echoes be displayed on the screen when the radar picks up the echoes. However, if there is a faulty point on the cable, the impedance at that point is different from the impedance elsewhere. When the impedance of a point on the line is not equal to the impedance Z of the line, the point will produce a total reflection or partial reflection echo.
We all know that sound travels at different speeds in different media, and pulse signals (electric waves) travel at different speeds in different cables. The formula s=V t: Calculate the time t for the instrument to reach the fault point by measuring the time from sending the pulse to receiving the echo, and we only need to replace the propagation velocity V of the cable to calculate the distance from the instrument measurement point to the fault point. This is the principle of cable fault location.
Of course, in real life, the cable is not necessarily directly buried, so the distance obtained from the cable fault location is not the straight-line distance, but the length of the cable. Although it can't directly guide us to find the point of failure, it is very helpful for us to greatly narrow the scope of inspection.
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