AC/DC clamp meter is also one of the necessary test tools in daily maintenance work. It is mainly used to test voltage, current, frequency and other related parameters, requiring high test resolution, test accuracy and more tests. Features. At present, the maintenance personnel usually use the F337 AC/DC dual-purpose clamp meter (true RMS) of FLUKE, which has large jaw diameter, high test resolution and precision, accurate small current and inrush current measurement. Features. At the same time, the humanized design of this type of clamp is very suitable for use in places with small space.
In the measurement of AC power parameters, a sampling method can be used. Through the comparison of various sampling methods, the characteristics of DC sampling method and various AC sampling methods and their applications are introduced in more detail.
The measurement method has high accuracy and good stability, but it is not suitable for multi-parameter measurement. Especially with the development of electronic technology, the processing speed of microcomputer and single-chip microcomputer is greatly improved, and there are also many kinds of products with good performance and price ratio. High-speed A/D converters provide advantageous hardware support for sampling and calculation methods.
The theory of the sampling calculation method is basically the sampling theorem, that is, the sampling frequency is required to be not less than twice the frequency of the highest harmonic of the signal. There are two main methods of power collection and calculation: one is DC sampling and the other is AC sampling.
DC sampling method DC sampling method, that is, sampling the rectified DC amount. When the voltage and current are measured by the DC sampling algorithm, the effective value of the electrical parameter is measured by measuring the average absolute value. The method is simple in software design and convenient in calculation, and only needs to be scaled to obtain the measured value. However, there are some problems with the DC sampling method, such as: the measurement accuracy is directly affected by the rectifier circuit.
The influence of degree and stability; the adjustment of the parameters of the rectifier circuit is difficult, and it is greatly affected by the form factor. At present, when the measured signal is a pure power frequency sine, the relationship between the effective value and the average absolute value
For: Urms=1.11Uaav, when the input signal contains harmonics, the relationship between Urms and Uaav will change, and the harmonic content is different, the relationship between the two is also different. This will bring errors to the calculation results. The analysis shows that the error of this measurement method can reach more than 10% in the case of serious harmonic pollution. The method of calculating power by DC sampling method usually calculates the effective values ​​of voltage and current and the phase angle between them separately, and directly substitutes them into the power calculation formula for calculation. In the case of harmonics, since the calculated voltage, current rms value and phase angle difference have large errors, the power calculation result will inevitably have a large error.
Soup Bucket,Disposable Soup Container,Biodegradable Paper Bowl,Food Packaging Bowl
JIANGYIN BIOPACKAGE CO.,LTD , https://www.chinapulppackage.com