Points for attention in the use of clamp ammeter
The external magnetic field has a great influence on the measured value, and it should be avoided as far as possible to measure near the busbar and large-capacity motor and other large load currents, otherwise the excessively high leakage magnetic field greatly exceeds the ability of the ammeter to defend against the external magnetic field, causing the ammeter to generate a large errors, leading to misjudgments.
Try to keep the wire in the center of the iron core jaws, the deviation from the center will make the measured value smaller and the negative error will increase. The meshing part of the split core should be completely meshed, and no foreign matter should be adhered to the contact surface, otherwise, the current value will become smaller and the negative error will increase due to the increase of the magnetic resistance.
Before measurement, estimate the magnitude of the current or voltage, select a suitable range, or select a higher range for measurement first, and then switch to a lower level successively depending on the measured current and voltage readings. And try to keep the pointer at about half of the full scale to get a more accurate reading.
During the measurement process, the range file must not be switched. Because there are many secondary turns in the clamp meter, the secondary turns are equivalent to a short circuit state during measurement, and the internal resistance of the meter head is ignored. Once the measuring range is switched during the measurement, it will cause the secondary instantaneous open circuit, and then a high voltage will be induced in the secondary winding, which may cause the interlayer or interturn insulation breakdown of the winding.
Multiple wires are drawn out from one terminal board, and when all the wires cannot be clamped in, the currents can be measured separately, and then the arithmetic sum of all the measured values can be taken.
When measuring small current, if the wire length has a margin, it can be measured by passing the wire through the iron core for several turns, and then take the indicated value divided by the number of turns passed to get the loop current
the actual value of .
For clamp current with AC voltage measurement
Table, the measurement of current and voltage should be carried out separately, and must not be carried out at the same time.
When measuring with a clamp meter, the watch handle should be wiped clean in advance, and the electrician's hands should be dry or wear insulating gloves.
After the measurement, be sure to set the adjustment switch to the maximum range position, so as to avoid damage to the instrument due to unselected range in the next use.
