The main part of the power line fault tester is composed of three main parts: the cable routing instrument, the main body of the power cable fault tester, and the cable fault locator. The cable fault locator is to determine the precise position of the cable (power line) fault point on the basis of the cable fault tester host determining the approximate position of the cable fault point. The main unit of the cable (power line) fault tester is used to measure the fault nature of the cable fault, the total length, and the approximate position of the cable fault point from the test end. For buried cables (power lines) with unknown directions, a path meter is required to determine the underground direction of the cables (power lines). The basic method for testing power cable faults is to apply a high-voltage pulse to the faulty power cable to generate a breakdown at the fault point of the cable (power line), and the cable (power line) fault breakdown point discharges and generates electromagnetic waves and sounds at the same time.
How to use the instrument:
The three-pulse method uses the double-impact method to prolong the arcing time and stabilize the arc, which can easily locate high-resistance faults and flashover faults. The three-pulse method has advanced technology, simple operation, clear waveform, fast and accurate positioning, and has become the mainstream positioning method for high-resistance faults and flashover faults. The three-pulse method is an upgrade of the two-pulse method. The method is to first measure the reflected waveform of the low-voltage pulse without puncturing the fault point of the cable (power line) under test, and then use the high-voltage pulse to break down the cable (power line). When the arc voltage drops to a certain value, a medium-voltage pulse is triggered to stabilize and prolong the arc time, and then a low-voltage pulse is issued to obtain the reflected waveform of the fault point. After the two waveforms are superimposed, the divergence can also be found. The point is the location corresponding to the fault point. It is easier to obtain the fault point waveform than the secondary pulse method due to the use of medium voltage pulses to stabilize and prolong the arc time. Compared with the second pulse method, because the third pulse method does not need to select the synchronous duration of the arc, the operation is also more convenient.
The working principle of the application of the arc reflection method (second pulse method) in the fault location of the cable (power line): first, a high-voltage pulse with a certain voltage level and certain energy is applied to the faulty cable (power supply line) at the test end of the cable (power line). line), allowing a breakdown arc to occur at the high-resistance fault point of the cable. At the same time, a low-voltage pulse for measurement is added to the test end. When the measurement pulse reaches the high-resistance fault point of the cable (power line), it encounters an arc and reflects on the surface of the arc. Since the high-resistance fault becomes an instantaneous short-circuit fault during arcing, the low-voltage measurement pulse will have obvious impedance characteristic changes, so that the waveform of the flashover measurement becomes the low-voltage pulse short-circuit waveform, making the waveform identification particularly simple and clear. This is what we call the "second pulse method". The reflected waveform of the received low-voltage pulse is equivalent to the waveform of a complete short circuit of a wire core to the ground. The low-voltage pulse waveforms obtained when the high-voltage pulse is released and when the high-voltage pulse is not released are superimposed, and the two waveforms will have a divergence point, which is the reflected waveform point of the fault point. This method combines the low-voltage pulse method with the high-voltage flashover technique, making it easier for testers to determine the location of the fault point. Compared with the traditional test method, the advanced point of the secondary pulse method is that the complex waveform in the shock high-voltage flashover method is simplified to the simplest low-voltage pulse short-circuit fault waveform, so the interpretation is extremely simple, and the fault distance can be accurately calibrated.
