Discussion on the problem of checking leakage and stealing electricity with clamp ammeter
With regard to the usage of clamp ammeter, a clamp ammeter is used to check whether there is any leakage on low-voltage lines and whether there is any electrical behavior on lines. The main operations include measuring leakage current, judging the location of leakage, and detecting whether there is any leakage on internal lines and equipment of users.
Check the leakage and stealing of electricity with clamp ammeter
1. Judge whether the residual current action protector is normal.
At the distribution transformer, disconnect the fuse on the phase line of the outlet side of the AC contactor that controls the low-voltage line. If the residual current action protector can be put into operation normally at this time, it means that the residual current action protector is good; Otherwise, the residual current action protector should be overhauled and replaced.
2. Measure the leakage current
At the distribution transformer, disconnect the neutral line on the outlet side of the AC contactor that controls the low-voltage line. Then, after the removed fuse core is installed in one phase, the phase is measured with a clamp ammeter, and the measured current is the leakage current of the phase.
Finally, according to the same method, measure the leakage current of other leakage phases in turn.
In order to prevent the phenomenon that the instrument is damaged by large current due to the grounding of the phase line on the line, the clamp ammeter should be placed on the large current block first when checking; If the detection current is small, then gradually reduce the gear.
3. Determine the location of the leakage
When the phase line with leakage is determined, the leakage position can be further judged.
(1) Detection at the distribution transformer.
At the distribution transformer, plug the phase line to be checked into the fuse core, and the fuses of the neutral line and the other two phases are disconnected. Check the live phase line with a clamp meter to determine the leakage position.
In order to improve the efficiency, the pole can be placed in the middle of the line, and it can be judged whether the leakage part is in the first half or the second half of the line through detection, and then it can be detected in the line section suspected of leakage, and so on, so as to narrow the detection range.
Finally, the phase line post insulator in a certain small range is detected, and the phase line of the user line connected to the phase line in this range is detected, which can be carried out on the ground or at the same time when the insulator is detected to determine the specific part of leakage.
(2) Detection at the user connection.
In the case of low-voltage line power transmission, the clamp meter can also be used to detect the connection line of low-voltage subscriber line with the suspected range.
When testing, the phase line and neutral line of single-phase electricity users should be placed in the jaws of the clamp meter at the same time, and the three phase lines and neutral lines of three-phase electricity should also be placed in the jaws at the same time.
If there is no leakage fault, then the vector sum of load current and magnetic flux is zero, and the indication of clamp table is also zero; If there is leakage current, the clamp ammeter can detect the leakage current.
4. Check whether there is any leakage in the user's internal lines and equipment.
The specific method is to measure the leakage current at the user's power inlet line with a clamp meter, and at the same time, put in and out the user's electrical equipment and lamps one by one, and find out the leakage equipment and lamps by looking at the change of leakage current detected by the clamp meter.
If all the equipment and lamps are in good condition, or the equipment with leakage has been withdrawn, but the clamp ammeter shows that the user still has leakage current, it may be that the user's low-voltage line has leakage and should be treated according to the specific situation.
For the leakage fault of buried pipeline, we can only take the treatment method of changing lines or rewiring.
5. Check the problems that should be paid attention to in leakage and stealing electricity.
When looking for leakage fault, it takes a short time to forcibly send electricity to control the AC contactor of low-voltage line.
When looking for leakage faults, pay attention to safety, must be supervised, and take safety protection measures. Note that when reading the data of the clamp meter, you must keep a safe distance between the human body and the charged part.
