Precautions when measuring with a clamp ammeter
Firstly, when using, tighten the wrench to open the jaws, place the measured wire in the center of the jaws, then release the wrench and close the jaws tightly. If there is any noise on the joint surface of the jaws, they should be opened and closed again. If there is still noise, the joint surface should be treated to ensure accurate reading. Additionally, it is not allowed to clamp two wires at the same time. After reading, open the jaws and exit the tested wire. Set the gear to the highest current or OFF position.
Secondly, the appropriate range of the clamp type ammeter should be selected based on the magnitude of the measured current. The selected range should be slightly larger than the measured current value. If it cannot be estimated, to prevent damage to the clamp ammeter, the measurement should start from the maximum range and gradually change gears until the range is appropriate. It is strictly prohibited to switch the gear of the clamp ammeter during the measurement process. When shifting gears, the measured wire should be removed from the clamp first and then the gear should be changed.
When measuring currents below 5 amperes, in order to make the reading more accurate, if conditions permit, the measured current carrying wire can be wound several times and placed in a clamp for measurement. At this time, the actual current value of the tested wire should be equal to the reading value of the instrument divided by the number of turns of the wire placed in the clamp.
When measuring, attention should be paid to maintaining a safe distance between all parts of the body and charged bodies. The safe distance for low-voltage systems is 0.1-0.3 meters. When measuring the current of each phase of high-voltage cables, the distance between cable heads should be at least 300 millimeters, and the insulation should be good. The measurement can only be carried out when it is deemed convenient. When observing the timing of the watch, special attention should be paid to maintaining a safe distance between the head and the charged part. The distance between any part of the human body and the charged body should not be less than the entire length of the clamp shaped watch.
When measuring the current of low-voltage fuses or horizontally arranged low-voltage busbars, the fuses or busbars of each phase should be protected and isolated with insulating materials before measurement to prevent phase to phase short circuits. When a cable is grounded, measurement is strictly prohibited to prevent the occurrence of ground breakdown and explosion due to low insulation level of the cable head, which may endanger personal safety.
