January 16, 2021. New energy cable There are three main methods for finding breakpoints: the method of energizing capacitance, the combination of capacitance method and induction method, and the combination of constant current source and bridge method.
1： Method of energizing capacitor
In this regard, some cable manufacturers usually use the capacitance comparison method to find the approximate location of the broken wire. It is inefficient to use the continuous power on method to accurately locate the cable disconnection point. Generally, it takes about 1.5 hours to find a breakpoint. This method is almost impossible to find broken cores for flame retardant cables whose shielding, armouring and sheath processes have been completed. If the construction is not good, the flame retardant cables will be scrapped. This method is basically no longer used.
2： Combination of capacitance method and induction method
This method is used for the broken core of the cable core, which requires that there is no metal coating outside the cable core and no extruded sheath. When searching, first use capacitance to find out the approximate position of the cable break, and then use the induced voltage method to accurately find the break point. This method is very simple and fast, and is also the most widely used method at present. The induced voltage method is to connect 650V AC voltage at one end of the broken core of the cable, and ground the other end and other cores, and then test with an inductive pen that can send optical signals. When the inductive pen slips from the broken core, 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 cable or cable core with metal layer. The method of using is to burn and break down the insulation at the broken core of the flame-retardant cable with a constant current source first, and then use the bridge fault locator to accurately locate the fault point, which is also a frequently used method.
