How to detect the broken core of Teflon insulated wire
Date：2021-11-26
What are the methods to detect the broken core fault point of Teflon insulated wire? Next, Xiaobian will tell you about it.
A. Induction method
1) Suspend the cable core to ensure that it will not cause road and electric shock accidents; At the same time, ensure that the cable is as far away from the grounding body as possible (such as ground, equipment, etc.);
2) Select the intact insulating core in the cable and connect it to the 220 VAC phase line (live line);
3) If an inductive pen is used, touch the inductive contact on the pen with your finger and test whether the pen is normal to determine whether it is outside the insulating layer of the charged body. If a digital multimeter is used, place it on a 20 or 200m pen, use a red plastic insulating sleeve and hold the black pen with your hand; During the test, the insulating layer shall be clear and the charge shall be read out, and then it shall be read far away from the charged body; Compare the difference between the two readings. Generally, there should be a higher reading on the charged body, such as 0.4 MV, and it will be lower away from the charged body, such as 0.15 MV; With this in mind, you can start testing.
4) If the pen indicator is found to be dimmed or the multimeter reading is significantly reduced, the test shall be carried out close to the cable.
5) After the test, pay attention to discharge!
B. Capacitance method
1) Hang all insulated core conductors and armor layers at both ends of the cable;
2) Determine the intact insulation core, the capacity value between the fracture of the insulation core and the steel strip, and record this value; At this time, the integrity of the insulating core shall be quite close to the capacitance value; When the capacitance values at both ends of the same broken core are added at the same position, there is only one breakpoint or multiple breakpoints; When the distance is very close, if the capacitance at both ends of the same broken core is less than at the same position, there are at least two breakpoints;
Note: theoretically, if there are only one or more breakpoints but they are very close, the sum of the capacitance values at both ends should be greater than the capacitance value maintained by the insulating core at the same position. The amount varies with different cables. See the theoretical analysis below.
3) The end length is determined by comparing the capacitance of the broken core insulating core and the insulating core. At this time, the length may be different from the actual length, and it must be corrected again in the next step; However, if the two cores are not armored, they cannot be corrected.
4) If the sum of the calculated length is greater than the actual length, the actual position of the breakpoint is negative. If it is smaller than the actual length, the re value is distributed by the capacitance of the insulating core. The long section of the large section is modified and the small section is changed to the short section (see the following theoretical analysis) to obtain the actual position of the breakpoint.
The above is the introduction brought by Teflon insulated wire. If you have any other questions, please call us.