Briefly describe the usage method of clamp ammeter
A clamp ammeter, also known as a clamp meter, is a specialized electrical instrument used to measure AC current. Generally used in situations where the circuit is continuously opened to measure current. Nowadays, most commonly used instruments are multifunctional digital displays or pointer displays.
The usage method of a clamp ammeter is simple, as shown in the above figure. When measuring current, simply clip the running wire 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, isn't it,
Just clamp the measuring wire. However, the widespread use of digital clamp ammeters has added many functions of a multimeter to clamp meters, such as voltage, temperature, resistance, etc. (sometimes referred to as clamp multimeters, as shown in the above figure, with two probe sockets on the instrument panel). Different functions can be selected by turning the knob, and the usage method is similar to that of a typical digital multimeter. For the meanings 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 an appropriate range range and do not use a small range to measure large currents. If the measured current is small, the current carrying wire can be wound several 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 off position) for safe use next time.
2. Do not switch the range during the measurement process.
3. Note that the voltage on the circuit should be lower than the rated value of the clamp ammeter. Clamp ammeters should not be used to measure the current of high-voltage circuits, otherwise it may cause accidents or electric shock hazards.
Firstly, select the voltage level of the clamp type ammeter correctly, check whether its appearance insulation is good, whether there is any damage, whether the pointer swings flexibly, and whether the clamp mouth is corroded. Estimate the rated current based on the motor power to select the range of the meter.
When measuring, the jaws of the clamp type watch should be tightly closed. If there is any noise after closing, the jaws can be opened and reset once. If the noise still cannot be eliminated, the joint surfaces on the magnetic circuit should be checked for smoothness. If there is dust, it should be wiped clean.
The clamp meter can only measure the current of one phase wire at a time. The measured wire should be placed in the center of the clamp window, and multiple phase wires cannot be clamped into the window for measurement.
Due to the low accuracy of the clamp ammeter itself, the following method can be used to measure small currents: first, wrap the wires of the tested circuit a few times, and then place them into the clamp of the clamp ammeter for measurement. At this point, the current value indicated by the clamp meter is not the actual value being measured. The actual current should be the reading of the clamp meter divided by the number of turns the wire is wound.
Measure the working current of the cage type asynchronous motor during operation. Based on the current level, it is possible to check and determine whether the motor is working properly to ensure safe operation and extend its service life.
