How to find broken overhead cables

The core of the cable is an important part of overhead cable. We transmit information through the core of the cable. If the core of the cable is broken, it will bring a lot of troubles and dangers. If the core of the cable is broken, how should we check? Someone may I would say to take a multimeter, but if it’s a big project, can’t I also use a multimeter?
One, the method of energizing the capacitor
Some cable factories usually use the capacitance comparison method to find the approximate location of the disconnection. Using continuous power-on method to accurately determine the disconnection point of the cable, the efficiency of this method is very low. Generally, it takes about one and a half hours to find a disconnection point. With this method, it is almost impossible to find a broken core for flame-retardant cables whose shielding, armoring, and sheathing processes have been completed. If it is not done properly, the flame-retardant cable will be scrapped. This method is basically no longer needed.

2. Combination of capacitance method and induction method
This method is used for the broken core of the cable core, which requires that LV ABC  cable core is not covered with a metal layer and there is no extruded sheath. When searching, first use the capacitor to find the approximate location of the cable disconnection, and then use the induced voltage method to accurately find the disconnection point. This method is very simple and quick, and it is also the most used method at present. The induction voltage method is to connect one end of the broken core of the cable with an AC voltage of 650V, and the other end and other cores are grounded, and then test with a sensor pen that can emit light signals. When the sensor pen slides over the broken core during the test, The signal will change, so that the cable break point can be accurately found.

3. Combination of constant current source and bridge method
This method is used for finished cables or cable cores that have been coated with a metal layer. Use is to find the method is to burn the insulation at the broken core of the flame-retardant cable with a constant current source and breakdown, and then use the bridge method fault locator to accurately locate the fault point, which is also a frequently used method.