How to use and recognize a clamp ammeter
1. Head-end measurement and judgment. First, power off the leakage circuit in the power distribution room (box). After verifying that there is no voltage, remove the three-phase fuses of A, B, and C of the circuit and untie the neutral line (N) (if there is no fuse, untie the circuit outlet wires, including the neutral line, and mark the neutral line) and the phase sequence of other phase lines). Connect the four wires in parallel, take any live wire and send it to power, so that all four wires are energized by a single fire. At this time, high and low voltage clamp ammeters can be used to measure the four wires respectively. If the measured current value of the Gan line shows a large value, while the values of the other three wires are very small or zero, it means that the one with a large current value has a serious leakage fault. If the four-wire measurement shows a large reading, it means that each phase has varying degrees of leakage. No matter what situation you encounter, gradually find the leakage fault point according to the principle of first increasing the current value and then decreasing it.
2. Confirm the first shot again. After the leakage fault phase has been determined at the head end of the power distribution room (box), use an insulating rod-type clamp ammeter on the base outlet pole to confirm the serious leakage fault phase with a large value again, and remember the fault phase. Then measure and search step by step along the fault phase to the power receiving side.
3. Search for T-shaped branches. When encountering a T-shaped branch line measurement and search, use the T-shaped branch pole as the benchmark, first measure the main line A1 point (direction of the power receiving side), and then measure the branch line A2 point. For example, it is measured that the leakage value of the A1 main line measurement point is large, but there is no leakage display at the A2 point. This means that the leakage fault point is still at the rear section of the main line, not on the T-shaped branch line.
4. Search for cross branches. When encountering a cross branch line measurement and search, take the cross branch pole as the benchmark and first measure the main line A1 point (direction of the power receiving side). If there is no leakage display, it means that the fault point is at point A2 (side "10" of the branch line) or point A3 (side "1" of the branch line). If there is leakage current at points A2 and A3 at the same time, it means there are multiple ground faults. Find the leakage fault points step by step according to the principle of first increasing the current value and then decreasing. By analogy and step by step, you can quickly find the serious leakage fault point or user. This method is also very fast and accurate in finding electricity theft at one line or one place.
