TDR

Same as in radar.Please try to search in wikipedia.

1 minute lessor:

A Time Domain Reflectometer (TDR) is connected to the de-energized conductor in question. It sends a very small "pulse" of energy down the conductor that travels along nicely as long as there is no break or short in it. As soon as it comes upon a bad condition, the pulse is reflected back to the source. By monitoring the pulse and reflection, you can use "time of flight" calculations to get the distance from the connection point to the fault.

If you want to know more details, there are myriad papers published on the internet for you to peruse. I've even seen a couple of good videos that explain it very well. Here's one.

thank You. Is ther any factors to be considered while checking cable faults of different cables using TDR. Like is there any different setting to made for coaxial or Power/control cables

Thank You folks. Is there any different factors to be considered while checking the coaxial and power/control cables.