Measurement process and measurement error 1. Measurement process The most measured process of various side-instrumentation instruments. Its essence is the continuous transformation and transmission of the most variable signal energy of the side-change, and the process of comparison between the well and the corresponding measurement unit. The detection instrument is to achieve This comparison tool, for example, detects the furnace and often uses the thermoelectric effect of the thermocouple to convert the side thermal energy into a DC millivolt signal (electric energy), which is then converted into a pointer displacement by the millivolt detection instrument. , and then compared with the temperature scale to show the measured value of the degree of judging. 2. Measurement error In the measurement process, due to the inaccuracy of the measurement tool used, the subjective nature of the observer, the influence of the surrounding environment, etc., the results on the side can not be absolutely accurate. There is always a certain gap between the value of the instrument side basin and the true value of the side parameter, and this difference is called the measurement error. Classification of errors According to the law of error, the side t error is divided into three categories: systematic error, random error and sulfur error.
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1 Systematic error: Under the same condition of the magnetic float level gauge, when the same side-parameter is repeated several times, the small and the sign of the error will remain unchanged, or the error that changes according to a certain rule when the condition changes. system error. If the instrument itself is flawed, the errors caused by changes in the single-factor environmental conditions such as tear, humidity, and electrical voltage are all systematic errors.
The characteristic of systematic error is that once the condition of the side basin is determined, the error is an exact value. Use the most average method for multiple measurements. The well cannot change the size of the error. Systematic errors are regular. Certain technical measures can be taken to correct the root causes of the changes, but they cannot be completely eliminated.
2 random error (occasional error): Under the same conditions, when repeated measurement t is performed on the same side parameter for many times, the error whose size and sign are changed in an unpredetermined manner is called random error. For example, the error caused by the electromagnetic field stem and the irregular changes of the sensory organs of the measurer are all random errors.
Random errors are measured several times. The overall obeys the statistical laws and most of them follow the normal distribution. They have symmetry, boundedness, compensation, and unimodality. The effect of random errors on the measurement results can be reduced by taking arithmetic mean values ​​for multiple measurements.
3 Inadvertent error: under a certain amount of lateral conditions, the error caused by the stem caused by artificial causes, and the value significantly deviated from the actual value is called negligence error.
The main causes of negligence errors are: Observer fatigue, lack of experience, improper operation, or lack of sense of responsibility resulting in errors such as misreading scales, wrong numbers, or calculation errors. As well as the sudden changes in the conditions of the two-color level gauge, such as mechanical impact caused by instrument changes in the indicator value.
The error can be overcome and it has nothing to do with the meter itself. Any side volume data that determines the missed error should be eliminated.
According to the different conditions of use of the instrument, the measurement error is divided into basic error and additional error. The basic error refers to the maximum error when the instrument is used under the specified standard working conditions. It is generally the allowable error of the instrument. The additional error is the error generated when the instrument is used under non-standard operating conditions, such as additional temperature error, additional error of electrical X fluctuation, and so on.