When our electricians need to measure the current without disconnecting the circuit, we need to use a clamp ammeter (referred to as clamp meter, clamp meter). A clamp-on ammeter is an instrument used to measure the magnitude of the current in a running electrical circuit, and is a commonly used measuring tool by electricians. Clamp-type ammeters are divided into two categories: clamp-type AC current meters and clamp-type AC and DC meters, and some can also measure AC voltage.
structure
The clamp-type AC ammeter is essentially composed of a current transformer and a rectifier instrument. The current-carrying wire to be measured is equivalent to the primary winding of the current transformer, and the secondary winding of the current transformer is on the iron core. , the secondary winding is connected to the rectifier system instrument. According to a certain proportional relationship between the primary and secondary windings of the current transformer, the instrument of the rectifier system can display the current value of the measured line.
The clamp-type AC/DC meter is an electromagnetic system instrument. The measured current-carrying wire placed in the jaw is used as the excitation coil. The magnetic flux forms a loop in the iron core. The electromagnetic measuring mechanism is located in the middle of the gap of the iron core. Deflection to get a reading. Since the deflection is not affected by the measurement current, AC and DC currents can be measured.
Instructions
The use of the clamp ammeter is simple. As shown in the figure below, when measuring the current, you only need to clamp the running wire to be measured into the clamp iron core of the clamp ammeter, and then read the reading on the digital display screen or the indicator panel. Can. It is very simple to use, just clamp the measuring lead. However, the widespread use of digital clamp current meters has added many multimeter functions to the clamp meters, such as voltage, temperature, resistance, etc. There are two test pen jacks), you can select different functions through the knob, and the use method is almost the same as that of a general digital multimeter. For the meaning of some special function buttons, please refer to the corresponding manual.
In addition, the following issues should be paid attention to when using the clamp ammeter:
1. Select the appropriate range block. You cannot use the small range block to measure large current. If the measured current is small, you can wrap the current-carrying wire a few more turns and put it into the jaw for measurement, but the reading should be divided by the winding coil. After the count is the actual current value. After the measurement is completed, the adjustment switch should be placed in the maximum range block position (or off position) for safe use next time.
2. Do not switch the range block during the measurement process.
3. Note that the voltage on the circuit should be lower than the rated value of the clamp meter, and the clamp ammeter cannot be used to measure the current of the high-voltage circuit, otherwise, it is easy to cause accidents or cause electric shock.
