The best way to use a clamp ammeter to check for leaks
The measured circuit wire passing through the iron core becomes the primary coil of the current transformer, and the current is induced in the secondary coil by passing the current. So that the ammeter connected to the secondary coil has an indication ----- measure the current of the line under test. The clamp meter can be changed to different ranges by changing the gear of the switch. But it is not allowed to operate with electricity when shifting gears. The clamp meter is generally not high in accuracy, usually 2.5 to 5 grades. For the convenience of use, there are switches of different ranges in the meter for the function of measuring different levels of current and measuring voltage.
When measuring current with a clamp ammeter, be sure to clamp a wire (wire) under test. If two (parallel wires) are sandwiched, current cannot be detected. In addition, when the center (core) of the clamp ammeter is used for detection, the detection error is small. When checking the power consumption of home appliances, it is more convenient to use a line splitter. Some line splitters can amplify the detection current by 10 times, so the current below 1A can be amplified before detection. When detecting DC current (DCA) with a DC clamp ammeter, if the current flows in the opposite direction, it will display a negative number. This function can be used to detect whether the car's battery is charged or discharged.
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 on one of the phases, then use a clamp ammeter to measure the phase. The obtained current is the leakage current of the phase. Measure the leakage current of the other leakage phases sequentially in the same way. In order to prevent the occurrence of large current damage to the meter due to the occurrence of phase wire grounding on the line (such as someone using the one-line-one-place method to steal electricity, etc.), the clamp ammeter gear should be placed on the high current gear when testing; if the detection value is small, then Switch the gear of the clamp ammeter to mA gear for detection.
After determining the phase line with leakage, the method for determining the location of leakage is: at the distribution transformer, insert the phase line to be checked into the fuse core, disconnect the fuses of the neutral line and the other two phases, and use it to climb the pole. The clamp ammeter detects the live phase wire to determine the leakage position. In order to improve efficiency, the position of the boarding pole can be selected in the middle of the line. Through detection, it is determined whether the leakage site is in the first half or the second half of the line, and then the line section where the leakage is suspected is detected. By analogy, the detection range is narrowed. Finally, detect the phase wire support insulator within the determined small range, and detect the phase wire of the user connection line connected to the phase wire within the range (it can be carried out on the ground, or when the insulator is detected Simultaneously) to determine the specific location of the leakage.
In the case of low-voltage line power transmission, the clamp ammeter can also be used to detect the low-voltage user connection lines within the suspected range. When testing, the phase wires and neutral wires of single-phase users should be placed in the jaws of the clamp ammeter at the same time, and the three phase wires and neutral wires of three-phase users should also be put into the jaws at the same time. If there is no leakage fault, the phasor sum of the load current magnetic flux is zero at this time, and the indication of the clamp ammeter is also zero; if there is a leakage current, the clamp ammeter can detect the leakage current.
The method to check whether there is any leakage in the user's internal lines and equipment is: use a clamp ammeter to measure the leakage current at the user's power inlet line, and at the same time put the user's electrical equipment and lamps into and out one by one, and check the leakage current by looking at the clamp ammeter 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 the low-voltage line of the user has leakage, and it should be handled according to the specific situation. For the leakage fault of the pre-buried and concealed pipeline, only the treatment method of changing the line or rewiring can be adopted.
