Clamp Ammeter - Introduction to Accuracy Requirements
(1) When measuring current, the gear position of the clamp ammeter should be selected appropriately. It is best to make the needle fall on the scale above 1/3 of the scale, because the deflection angle of the needle is too small, and the scale value is not easy to distinguish, which affects the measurement. the accuracy.
(2) The measured wire should be placed in the center of the jaws as much as possible. If the measured wire is too skewed, the magnetic induction intensity generated by the measured current in the jaw core will have a large change, which will directly affect the measurement. Generally, the measurement error caused by the improper position of the measured wire in the jaw can reach 2%-5%.
(3) In order to make the reading accurate, the two sides of the iron core jaw should be tightly closed. If you hear electromagnetic noise from the jaws or feel a slight vibration in the hand holding the clamp ammeter, it means that the end faces of the jaws are not tightly bonded. At this time, the jaws should be re-opened and closed; if the noise still exists, check the jaws. Check whether there is any dirt or rust on the end surface of the jaws. If there is any, it should be cleaned until the jaws are well combined.
(4) For the digital clamp ammeter, although the battery power has been checked before use, you should always pay attention to the battery power during the measurement process. If the battery voltage is found to be insufficient (such as a low voltage prompt symbol), The measurement must be continued after the battery is replaced; if there is electromagnetic interference at the measurement site, it will inevitably interfere with the normal progress of the measurement, so try to eliminate the interference. Whether the measurement data can be read correctly is also directly related to the accuracy of the measurement.
(5) For the meter head of the pointer clamp meter, firstly, check the selected gear, and secondly, check which scale is used. When observing the scale value pointed by the hands of the watch, the eyes should face the hands and the scale directly to avoid strabismus and reduce parallax. Although the display of the digital meter is relatively intuitive, the effective viewing angle of the LCD screen is very limited. It is easy to read the wrong number when the eyes are too skewed. You should also pay attention to the decimal point and its position, which must not be ignored. .
(6) Abnormal or drastic changes in the temperature of the measurement site will affect the accuracy of the measurement. Because changes in temperature will increase the error of the meter, thereby reducing its accuracy. The main reason why the clamp ammeter is affected by temperature is that the temperature change changes the results of the material properties of the key structural parts of the meter. For example, after the ambient temperature changes, the elasticity of the balance spring that produces the reaction torque of the meter often changes, so that the value of the meter changes accordingly, and the magnetic field of the magnetic field that forms the magnetic field changes, so that the magnitude of the acting torque of the meter changes. In addition, due to changes in ambient temperature, the resistance of the circuit that constitutes the instrument, as well as the parameters of various electronic components and semiconductor devices will change, and the final result will affect the accuracy of the measurement.
(7) During the measurement process, two or more wires cannot be clamped at the same time. When measuring a current less than 5A, in order to obtain a more accurate reading, if conditions permit, the wire can be wound several times and put into the jaw for measurement, but the actual current value should be the reading divided by the number of coils put into the jaw .
