By hvhipot 
Based on common faults in power cables, HV Hipot Electric Co., Ltd. company’s HT-TC cable fault tester has designed fHV Hipot Electric Co., Ltd. testing methods. Users can adopt different testing methods according to different faults, or use different methods to collect waveforms separately, compare and analyze them with each other, and further confirm the fault point.
1. Principle of Cable Fault Testing
The basic principle used to test cable faults with HT-TC cable fault tester is the “echo test” principle, which relies on the transmission and reflection of radio waves in the cable for testing.
⑴ Pulse method testing principle: Pulse method testing generates a pulse wave inside the instrument, which is applied to the cable. When the pulse wave encounters a point where the cable characteristic impedance changes, it will generate an echo signal (according to the transmission line principle). The instrument collects and displays these two signals (transmission wave and echo) at the testing end of the cable, and calculates the distance between the fault point and the testing end based on the time difference between these two waves. Therefore, this testing method is not affected by cable laying rules and is only related to the transmission speed of radio waves in this cable.
⑵ High voltage flashover method testing principle: When dealing with high resistance faults in cables, external equipment is used to apply high voltage to the cable. When the faulty cable cannot withstand the applied high voltage, a breakdown arc will occur at the fault point. The breakdown arc will generate an echo, so we can use a tester to record the entire breakdown process in the form of waveform acquisition at the testing end. Through this breakdown process, we can analyze and calculate the distance between the breakdown point and the testing end. Similarly, this testing method is not affected by cable laying conditions and is only related to the transmission speed of radio waves in this cable.
2. Cable Fault Testing Procedure
When using the HT-TC cable fault tester to test cable faults, the following procedure should be followed:
（1） Use a multimeter, shake meter, or determine the nature of cable faults based on cable pre test results.
（2） Select appropriate testing methods based on the nature of cable faults: pulse method is best used for low resistance faults and open circuit faults, although flashover method can also be used for low resistance faults. It is best to use the flashover method (L method) for leakage high resistance faults, and some leakage high resistance faults can also use the direct flashover method, but this is usually not done. For flashover high resistance faults, it is best to use the direct flashover method, or both methods can be tested and compared to improve the accuracy of judgment.
（3）Test the total length of the cable using pulse method to calibrate the radio wave transmission speed of the tested cable.
（4）Perform rough testing on the fault point according to the selected testing method. If one testing method is not ideal, other methods can be used for comparative testing.
（5）After the rough measurement is completed, locate the fault point.
（6）After the test is completed, if necessary, experience summary and error analysis can be conducted.