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Clamp-on ammeter to check leakage

time:2021/9/20   source:华天电力  reading:236 time

The clamp ammeter is a combination of a current transformer and an ammeter. The iron core of the current transformer can be opened when the wrench is tightened; the wire through which the measured current passes can pass through the opening of the iron core without cutting off, and the iron core is closed when the wrench is released. Now let me introduce you to the clamp-on ammeter to check the leakage, just for your reference. The clamp ammeter is a combination of a current transformer and an ammeter. The iron core of the current transformer can be opened when the wrench is tightened; the wire through which the measured current passes can pass through the opening of the iron core without cutting off, and the iron core is closed when the wrench is released. Now I will introduce you to the clamp-on ammeter to check the leakage, just for your reference.


1. The method to determine whether the residual current-operated protector itself has a problem is: 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-operated protector can be normal at this time Putting into operation, it is confirmed that the residual current operated protector is good. Otherwise, the residual current operated protector should be overhauled and replaced.


2. Check to determine which phase phase line leakage method is: at the distribution transformer, disconnect the neutral line on the outlet side of the AC contactor that controls the low-voltage line, and then install the removed fuse core in it. After one phase is on, measure the phase with a clamp ammeter, and the measured current is the leakage current of the phase. Measure the leakage current of the remaining leakage phases sequentially in the same way. In order to prevent the presence of phase-line grounding on the line (such as someone using one-line-one-ground method to steal electricity, etc.), the instrument should be damaged by high current. Clamp-on ammeter shift to milliampere shift detection


3. After determining the phase line with leakage current, the method of determining the location of the leakage current is: at the distribution transformer, plug the phase line to be checked into the fuse core, and the neutral line and the fuses of the remaining two phases are disconnected. The pole uses a clamp-type ammeter to detect the live phase line to determine the leakage position. In order to improve efficiency, the pole position can be selected in the middle of the line, and the leakage position is determined by detection in the first half or the second half of the line, and then to the line section where the leakage is suspected. By analogy, the detection range is reduced. Finally, the phase line pillar insulators within the determined smaller range are tested, and the user connection line phase lines connected to the phase line within the range are tested (can be performed on the ground or when testing the insulators. Simultaneously) to determine the specific location of the leakage. In the case of low-voltage line power transmission, the clamp-on ammeter can also be used to determine the low-voltage user connection line within the suspected range. When testing, the phase and neutral wires of single-phase users should be placed in the jaws of the clamp-on ammeter at the same time, and the root phase and neutral wires of three-phase users should also be placed in the jaws at the same time. If there is no leakage fault, the phasor sum of the load current flux is zero at this time, and the clamp ammeter indication is also zero; if there is a leakage current, the clamp ammeter can detect the leakage current.


4. Check the user's internal wiring and equipment for leakage current. The method is: use a clamp ammeter to measure the leakage current at the user's power supply line, and at the same time put the user's electrical equipment and lamps into and out one by one, and check by looking at the clamp type ammeter. Leakage current changes to find leaking equipment and lamps. If all the equipment and lamps are good, or the equipment with leakage has been withdrawn, but the clamp ammeter shows that the user still has leakage current, it may be that there is leakage in the user's low-voltage line, which should be dealt with according to the specific situation. For the leakage faults of buried pipelines, the only way to deal with it is to change the line or re-wiring.


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