Several issues that should be paid attention to when using clamp ammeter
The use of a clamp ammeter is simple. When measuring current, simply clamp the running wire to be tested into the clamp iron core of the clamp ammeter, and then read the reading on the digital display screen or indicator panel. It's easy to use, just clamp the measuring wire. However, the widespread use of digital clamp ammeters has added many functions to clamp ammeters, such as voltage, temperature, resistance, etc. (sometimes referred to as clamp multimeters, as shown in the figure on the right, with two probe sockets on the instrument). Different functions can be selected through knobs, and the usage method is similar to that of a general digital multimeter. For the meaning of some unique function buttons, reference should be made to the corresponding manual. In addition, when using a clamp ammeter, the following issues should be noted:
1. Choose the appropriate range gear
It is not allowed to measure high current with a small range gear. If the measured current is small, the current carrying wire can be wound a few more times and placed in the clamp for measurement. However, the actual current value should be obtained by dividing the reading by the number of coils wound. After the measurement is completed, the adjustment switch should be placed in the maximum range position (or closed position) for safe use next time.
2. Do not switch range gears during the measurement process
3. Note that the voltage on the circuit should be lower than the rated value of the clamp meter
Do not use a clamp ammeter to measure the current of a high-voltage circuit, otherwise it may cause accidents or pose a risk of electric shock.
The method of using a clamp ammeter to determine which phase of a low-voltage line is leaking electricity is as follows:
At the transformer distribution point, disconnect the neutral wire on the AC output side that controls the low-voltage line. Then install the removed fuse core on one of the phases, measure the phase with a clamp ammeter, and the measured current is the leakage current of that phase. Measure the leakage current of the remaining leakage phases in sequence using the same method.
In order to prevent the occurrence of high current damage to the instrument due to phase grounding on the line (such as someone stealing electricity by using a one line one ground method), the clamp current meter should be set to the high current position first when conducting the above detection; If the detection value is very small, switch the clamp ammeter to milliampere range for detection. When searching for leakage faults, it is necessary to forcibly power on low-voltage lines in a short period of time.
