How does the clamp ammeter judge the earth leakage fault point?
1. Judgment of earth leakage fault point by clamp ammeter
When a ground leakage fault occurs in a distribution line or a motor control device, it is difficult to find out the specific ground fault point. The method of judging leakage grounding faults with a clamp ammeter does not require power outages or wiring.
Second, the clamp ammeter method to determine the leakage grounding fault point
When a ground leakage fault occurs in a distribution line or electrical equipment, it is difficult to find out the specific ground fault point.
The method of using clamp ammeter to measure leakage grounding fault in low-voltage power grid has the advantages of no need for power outage, light equipment, no wiring for testing, intuitive reading, simple operation, etc. It can quickly and accurately determine the leakage grounding fault point.
If a ground leakage fault occurs in a certain phase line or equipment, you can first test power transmission in phases on the main switch of the low-voltage power supply in the power distribution room. The method of temporarily removing other two-phase fuses can be used. Then, on the neutral point grounding wire of the distribution transformer T, the caliper ammeter, as shown in Figure 1, measures the neutral wire current of each phase line respectively. Generally speaking, the phase line with the larger neutral line is the line with a ground fault or a serious potential fault.
After the faulty phase line is determined, the main line of the phase line (three-phase four-wire power distribution part) can focus on checking whether the overhead line is broken and dropped to the ground, and the overhead line is connected to the wiring, telephone line and broadcasting line. Phase-to-ground short circuit fault.
After finding out that there is no problem with the main line, use a clamp ammeter to measure and check the single-phase branch line. The inspection and test method is shown in Figure 2.
After testing and confirming that there is a ground leakage fault in a certain branch line, you can use the "half method" to carry out key inspections on the branch line. From: Home of Electrical Technology
When it is found that there is a ground leakage fault in a certain user, use a clamp ammeter to check the user from the lamp holder, switch, socket, etc., and then further check the wires. During the inspection, attention should be paid to places where wires pass through walls, turn, cross, twist, and are easy to corrode, easy to be damp, and easy to be rolled by machinery and vehicles.
