What is the method of using cable fault tester low voltage pulse testing to measure cable fault points? After a power cable fault occurs, it will cause interruption of power transmission, and it is necessary to find the fault point as soon as possible and then repair it. Therefore, it is very important to find the fault point in time. Using a cable fault tester and the low voltage pulse testing method to measure cable fault points is not only fast but also safe. This article takes YTC630cable fault tester as an example to briefly introduce the method of using cable fault tester low voltage pulse testing to measure cable fault points.
The low voltage pulse testing method has the characteristics of simple operation, easy waveform identification, and high accuracy. For short circuit, low resistance, and open circuit faults, this method can be used to directly determine the fault distance. Even if there is no such fault, before general high voltage flashover testing, the low voltage pulse method can also be used to measure the full length or speed of the cable, and comparing with the flashover test waveform usually facilitates waveform analysis to achieve the purpose of quickly determining the fault point.
Method of measuring faults with low voltage pulse testing:
When the pulse menu appears, you can select key 1 (no full length) or key 2 (measure fault). Connect the cable to the tested cable fault in the same way, and other operation methods are the same as measuring full length. If it is a low resistance or open circuit fault, the test waveform is shown in the figure
When setting the cursor, the intersection of the rising edge of the transmitted positive pulse and the baseline is set as the starting point, and the intersection of the falling edge of the reflected negative pulse and the baseline is set as the ending point. If it is a short line fault, the test waveform and cursor setting method are the same as when measuring full length. When using the pulse method for testing, after connecting according to the figure, select the appropriate transmission speed and pulse width according to the type of cable being tested, adjust the input amplitude potentiometer to 1/3 position, and press the sampling key.
According to the displayed waveform size, adjust the amplitude potentiometer and resample. When the reflected wave is still not visible at the maximum input amplitude with 0.2us pulse width, use 2us pulse for testing. For easy comparison, you can sample twice by connecting the faulty phase and another good phase respectively, as shown in Figure 6 above. Press the ()(¯) keys to select single or dual waveform display, use the 1/2 key to change the operation area, and select current waveform 1 or 2. After completing sampling, move the cursor to set the starting point, then move the cursor to the waveform reflection point. At this time, the length displayed on the screen is the full length of the cable. For short cables, it is best to short-circuit the terminal to measure the full length. The terminal reflection changes to a negative pulse. When setting the cursor, for an open-circuit terminal cable, use the intersection of the rising edge of the transmitted positive pulse and the baseline as the starting point, and the intersection of the rising edge of the reflected positive pulse and the baseline as the ending point.
The low voltage pulse testing method has the characteristics of simple operation, easy waveform identification, and high accuracy. For short circuit, low resistance, and open circuit faults, this method can be used to directly determine the fault distance. Even if there is no such fault, before general high voltage flashover testing, the low voltage pulse method can also be used to measure the full length or speed of the cable, and comparing with the flashover test waveform usually facilitates waveform analysis to achieve the purpose of quickly determining the fault point.
The usage methods of cable fault testers produced by different manufacturers are similar. Therefore, power workers need to read the product instructions carefully before use and strictly follow the instructions to use them, so that cable fault points can be quickly located.
