What are the reasons for the error of the cable fault detector equipment

Although the cable fault detector equipment brings certain convenience in the cable fault detection. However, in practice, the cable fault detector equipment will cause deviations in the detection results due to various uncertain factors. So what are the reasons for the error of the cable fault detector?

Cable fault detector

Human error

At present, the cable fault detector developed on the principle of traveling wave method is mainly used by testers to judge and calculate the distance position of the fault point after analyzing the fault detection waveform. The interpretation error produced by the user is sometimes the detection error, which is usually related to the work experience of the detection point personnel, mainly in the application of detection methods, the test voltage level during the detection process, the connection details, and the judgment of the inflection point of the detection waveform. . This is also one of the main reasons why cable fault detection is more difficult than other electrical equipment fault detection. Due to the irregularity and complexity of the cable fault detection waveforms, it is currently difficult to achieve true automatic calculation and judgment of the location of the fault point.

Cable fault detector

Cable error

It is mainly the error caused by the transmission speed V of the electric wave on the cable under test. From the formula L=(U*T)/2, it can be seen that the cable fault detection distance L is proportional to V. In the cable fault detection, we say that V is a constant, it is a relative concept, not an absolute fixed value. The actual measurement and related data show that the transmission speed V can generally produce a relative error of ±2%. For example, the transmission speed V of the XLEP cable is about 172.3m/靤, and there are two reasons for the error of the transmission speed V: First, the same type of cables produced by different manufacturers may cause errors due to the production process and ingredients. Second, the aging of the cable insulation causes a change in V, and there is no accurate data to explain this trend. Note: There are inconsistencies among the marked length, actual length and detected length of the tested cable.

Cable fault detector

Environmental error

When the rough measurement of the cable fault is completed, the distance measurement is usually carried out according to the detection distance data along the direction of the cable. However, due to poor environmental conditions (such as rivers, trenches, buildings, etc.) and the winding of the buried cable, it is accurate. It is very difficult to measure, and a lot of time can only be a very rough and approximate designated location. This error is also called measurement error, and in many cases is a source of error that cannot be estimated. Therefore, it is very important to establish and improve the detailed files of power cables, and the digital management of pipe network GIS will be more indispensable in the future.

Cable fault detector

In addition to the above, the reasons for the error of the cable fault detector are other than the above, but other factors, such as equipment failure, etc., are also excluded. In order to avoid errors in the detection of the cable fault detector, we need to carefully analyze the data in the detection.