How to Use High and Low Voltage Clamp Ammeter to Quickly Find the Leakage Fault Point
The new method for quickly locating leakage fault points is the four wire single fire clamp meter method. The search steps are: first disconnect the main circuit breaker in the substation area, connect the low-voltage four wire outgoing lines (including the zero line) in parallel, then connect the one phase power supply, and then use the high and low voltage clamp Ammeter to measure and judge the leakage fault point phase by phase and level by level. The four wire single fire clamp meter method has small workload, fast fault point finding and low risk.
1. First end measurement judgment. Firstly, power off the leakage circuit of the distribution room (box). After verifying that there is no voltage, remove the three-phase fused neutral circuit breakers A, B, and C of the circuit and disconnect the neutral line (N) (if there is no fuse, disconnect the circuit outgoing line, including the neutral line, and mark the phase sequence of the neutral line and other phase lines). Connect four wires in parallel, take any phase of the live wire, and then power on, so that all four wires are powered on separately. At this time, use the high and low voltage clamp Ammeter to measure the four wires respectively. If the current value displayed on the Gan line is large, while the values of the other three lines are small or zero, it indicates that a serious leakage fault has occurred with a large current value. If there are significant readings in all four wire measurements, it indicates that each phase has varying degrees of leakage. Regardless of the situation encountered, gradually search for the leakage fault point based on the principle of increasing the current value first and then decreasing it.
2. Confirm the first shot again. After the leakage fault phase has been judged and confirmed at the head end of the distribution room (box), the insulation rod clamp Ammeter shall be used to confirm the serious leakage fault phase with large value at the base outgoing pole again, and the fault phase shall be firmly remembered. Follow the faulty phase and gradually measure and search towards the receiving side.
3. Search for T-word branches. When encountering the T-branch line measurement and search, use the T-branch pole as the reference, first measure the main line A1 point (in the direction of the receiving side), and then measure the branch line A2 point. If the leakage value at the measurement point A1 of the main line is large, but there is no leakage display at point A2. It indicates that the leakage fault point is still in the rear section of the main line, rather than on the T-branch line.
4. Search for cross branches. When encountering cross branch line measurement and search, take the cross branch pole as the reference and first measure the main line A1 point (in the direction of the receiving side). If there is no leakage display, it indicates that the fault point is at point A2 (on the "ten" side of the branch line) or point A3 (on the "one" side of the branch line). If there is leakage current at points A2 and A3 simultaneously, it indicates the presence of multiple grounding faults. Gradually search for the leakage fault point based on the principle of increasing the current value first and then decreasing it. By following this and gradually, serious leakage faults or users can be quickly identified. This method is also very fast and accurate in detecting wire to wire theft.
