The Method of Checking Leakage and Stealing Electricity with a Clamp Meter
A clamp type ammeter is a powerful tool for detecting low voltage line leakage or stealing electricity.
Determine if there is a problem with the residual current operated protector itself
At the distribution transformer, disconnect the fuse on the phase line of the AC contactor that controls the low-voltage line. If the residual current operated protector can be put into operation normally at this time, it proves that the residual current operated protector is good. Otherwise, the residual current operated protector should be repaired and replaced.
Check and determine which phase line has leakage
At the distribution transformer, disconnect the neutral wire on the outgoing side of the AC contactor that controls the low-voltage line, and then install the removed fuse core on one of the phases. Use a clamp ammeter to measure the phase, and the measured current is the leakage current of that phase. To prevent the presence of phase grounding on the line (such as someone using the one line, one place method to steal electricity, etc.) causing high current damage to the instrument, first place the clamp type ammeter in the high current position during testing; If the detection value is very small, then switch the clamp ammeter gear to milliampere gear for detection.
After determining the phase line with leakage, determine the location of the leakage
At the distribution transformer, insert a fuse core into the phase line to be inspected, disconnect the neutral line and the fuses of the other two phases, and use a clamp type ammeter to detect the live phase line on the pole to determine the leakage position. In the case of low voltage line power transmission, clamp type ammeters can also be used to detect low-voltage user connection lines within the suspected range. During detection, the phase 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 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 clamp ammeter indicates zero, otherwise it is not zero.
Check the user's internal wiring and equipment for leakage
Measure the leakage current at the incoming line of the user's power supply using a clamp type ammeter, and at the same time, put the user's electrical equipment and lamps into and out one by one. Check the changes in leakage current by looking at the clamp type ammeter to find the leaking equipment. If all devices are in good condition, or if devices with leakage have exited, but the clamp ammeter shows that the user still has leakage current, it is possible that the user's low-voltage line has leakage, and it should be handled according to the specific situation.
