Types and Usage of Clamp Meters
1. AC clamp ammeter
The AC clamp ammeter consists of a current transformer and a rectifier ammeter. When holding the wrench of the clamp shaped meter tightly, the iron core of the current transformer is opened, and it is used to cover the measured current wire, then the wrench is loosened. This wire serves as the primary winding of the current transformer, while the secondary winding on the iron core is connected to a magneto electric ammeter through a rectifier. According to the certain transformation ratio relationship between the primary and secondary windings of the current transformer, the rectifier instrument can display the current value of the measured line. By switching the conversion switch to change the transformation ratio of the current transformer, different ranges from one ampere to tens of thousands of amperes can be obtained.
2. AC/DC dual-purpose clamp current
The dual-purpose clamp ammeter for AC and DC is shown in the above figure. Its appearance is similar to that of an AC clamp ammeter, and it is composed of an electromagnetic measurement mechanism. When clamping the measured current wire, a magnetic field is generated in the iron core, and the moving iron plate of the measuring mechanism located at the gap of the iron core is deflected by the magnetic field to drive the pointer. Its working principle is similar to that of electromagnetic instruments, so it can be used to measure both AC and DC currents.
3. Multi purpose clamp ammeter
A multi-purpose clamp ammeter consists of a clamp transformer and a multimeter. When the connecting wire of the transformer is pulled out, the clamp does not work and can be used as a multimeter.
The use of clamp ammeter
1. Choose the appropriate range gear and do not 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. The actual current value should be obtained by dividing the reading by the number of coils wound. After the measurement is completed, the conversion switch should be placed in the maximum range position (or closed position) for safe use next time.
2. Do not switch the range gear during the measurement process to avoid bending the pointer; If gear shifting is required, the tested wire should be removed from the clamp first before shifting.
3. Please note that the voltage on the circuit should be lower than the rated value of the clamp current meter. It is not advisable to use a clamp current meter with a low voltage level to measure the current of a high-voltage circuit, otherwise it may cause accidents or pose a risk of electric shock.
4. During thunderstorms, it is prohibited to use clamp ammeters for measurement outdoors.
