How to check the leakage and stealing of low-voltage lines with clamp ammeter?
Clamp ammeter is a combination of current transformer and ammeter. The iron core of current transformer can be opened when the wrench is pinched; The wire through which the measured current passes can pass through the open gap of the iron core without cutting, and the iron core is closed when the wrench is spread out.
The tested circuit wire passing through the core becomes the primary coil of the current transformer, and the current is induced in the secondary coil after passing through it. Then the ammeter that connects the secondary coil will have instructions-measure the current of the tested line.
The clamp ammeter can change the different range by shifting the switch. However, it is not allowed to operate with electricity when shifting gears. The general accuracy of clip-on meters is not high, ranging from 2.5 to 5.
For the convenience of use, there are also switches with different ranges in the meter for measuring different grade current and measuring voltage.
When measuring current with a popular ammeter, it is very troublesome to cut off the circuit and stop it before connecting the ammeter for measurement. Sometimes the normal operation of the electric thought does not allow this.
At this point, it is much more convenient to use the clamp ammeter, and the current can be measured without cutting off the circuit. Clamp ammeter is the best thing to reflect on the leakage of low-voltage lines or to check the stealing of electricity.
1, judging whether there is a problem with the residual electricity activity as a maintainer itself.
Solution: At the distribution transformer, disconnect the fuse on the phase line of the outlet side of the AC contactor of the low-voltage line. If the residual electricity activity can be put into operation normally at this time, it is proved that the residual electricity activity is good. Otherwise, it should be overhauled and replaced as a maintainer.
2, reflect on which phase line is leaking.
Solution: At the distribution transformer, disconnect the neutral wire on the outlet side of the AC contactor of the controlled low-voltage line, then install the removed fuse core on one phase, and measure the phase with a clamp ammeter. The measured current is the leakage current of the phase. The leakage currents of other leakage phases are measured in sequence in the same way.
In order to avoid the phase line grounding (if someone does not have a partial discharge power frequency test transformer, automatic variable ratio tester, grounding on-resistance tester, frequency conversion series resonance test device, wireless high-voltage nuclear phase detector uses the one-wire-one-local method to steal electricity, etc.), the clamp ammeter is first placed in the high-current position during detection; If the detection value is very small, then switch the clamp ammeter gear to mA gear for detection. From: Home of Electrical Technology
3. After determining the phase line with leakage, judge the position of leakage.
Solution: At the distribution transformer, plug the phase line to be reflected into the fuse core, and the neutral line and other two-phase fuses are disconnected. When climbing the pole, use the clamp ammeter to detect the live phase line to determine the leakage status. In order to improve the efficiency, the pole-boarding position can be selected in the middle of the line, and the leakage part is determined in the first half of the line as in the second half after detection, and then it is detected in the line section suspected of leakage. By analogy, the detection limitation is reduced.
Finally, the phase line pillar insulator within a certain small limit is detected, and the phase line of the customer's grounding line with this limit is detected (either on the ground or when detecting the insulator) to determine the detailed part of the leakage.
