The brief introduction and use of clamp ammeter
It is worth noting that the principle of clamp ammeter is to use the principle of transformer, so whether the iron core is closed tightly or not and whether there is a lot of remanence has a great influence on the measurement results, and when measuring a small current, the measurement error will increase. At this time, the measured wire can be wound around the core several times to change the current ratio of the transformer, so as to increase the current range.
The principle of clamp ammeter is based on the working principle of current transformer. When the iron core of the loosening wrench is closed, an induced current is generated on its secondary winding according to the principle of transformer, and the pointer of ammeter deflects, thus indicating the value of the measured current. When the clamp ammeter wrench is gripped, the iron core of the current transformer can be opened, and the conductor of the measured current enters the jaw as the primary winding of the current transformer.
Attention should be paid to the following points when using clamp ammeter:
When timing the observation meter, special attention should be paid to keeping the distance between the head and the charged part, and the distance between any part of the human body and the charged body should not be less than the whole length of the clamp meter.
When measuring on the high voltage circuit, it is forbidden to connect another meter from the clamp ammeter with wires. When measuring the phase currents of high-voltage cables, the distance between the cable heads should be above 300mm, and the insulation is good. Only when the measurement is considered convenient can it be carried out.
When measuring the current of low-voltage fusible fuses or horizontally arranged low-voltage buses, all phases of fusible fuses or buses should be protected and isolated with insulating materials before measurement, so as to avoid short circuit between phases.
Pull the switch to the maximum range after the clamp ammeter is measured, so as to avoid inadvertent overcurrent when it is used next time; And should be kept in a dry room.
When the cable is grounded, it is forbidden to measure. Prevent the personal safety from being endangered by the ground breakdown explosion caused by the low insulation level of the cable head.
When using high voltage clamp ammeter, we should pay attention to the voltage grade of clamp ammeter, and it is forbidden to measure the current of high voltage circuit with low voltage clamp ammeter. When measuring with a high-voltage clamp meter, it should be operated by two people. Non-duty personnel should also fill in a safety working ticket when measuring. When measuring, they should wear insulating gloves and stand on insulating mats, so as not to touch other equipment to prevent short circuit or grounding.
