一、传感器的选择

1、 Selection of sensors

本文主要谈谈传感器的精度与衡器精度的关系。大家都说“传感器是衡器的心脏”，这说明衡器的精度和性能不可能超越其使用传感器的精度和性能。非自动衡器的R76号国际建议的制定早于称重传感器OIMLR60号国际建议。由于两者都是采用分段阶梯表示误差，根据误差的检定分度数和检定分度值来确定器件的大允许误差（mpe），并以此确定衡器和传感器的精度级，所以它们之间应满足以下条件。

This paper mainly talks about the relationship between the accuracy of the sensor and the precision of the weighing instrument. It is said that "the sensor is the heart of the weighing instrument", which shows that the accuracy and performance of the weighing instrument can not exceed the accuracy and performance of the sensor used. International recommendation R76 for non automatic weighing instruments was developed earlier than oimlr60 for load cells. Because both of them use subsection ladder to express the error, the maximum allowable error (MPE) of the device is determined according to the calibration scale and the calibration division value of the error, and then the accuracy level of the weighing instrument and the sensor is determined. Therefore, the following conditions should be met between them.

（1）根据R76的误差分配，规定传感器的分量系数为Pi=0.7。传感器的最大允许误差，为相应精度及衡器大允许误差（mpe）的0.7倍。

(1) According to the error distribution of R76, the component coefficient of sensor is defined as pi = 0.7. The maximum allowable error of the sensor is 0.7 times of the corresponding accuracy and the maximum allowable error of the weighing instrument (MPE).

（2）称重传感器的最大秤量必须大于衡器的大秤量Max。

(2) The maximum weighing capacity of the load cell must be greater than the maximum weighing capacity max of the weighing instrument.

（3）在整个使用范围内必须满足：n≤nmax，v≥vmin，nmax为称重传感器的最大检定分度数。vmin为传感器的最小检定分度值，它是由小载荷的温度影响来决定的。

(3) In the whole application range, it must meet the following requirements: n ≤ nmax, V ≥ Vmin, nmax is the maximum calibration division number of the weighing sensor. Vmin is the minimum calibration value of the sensor, which is determined by the temperature effect of the minimum load.

（4）2DR≤e，其中：DR为传感器的最小静载荷恢复值，e为衡器分度值，为首次检定大允许误差。

(4) 2DR ≤ e, where Dr is the minimum static load recovery value of the sensor, e is the scale value of the weighing instrument, and is the maximum allowable error of the first verification.

（5）相对DR，即Z=Emax（/2×DR），该比值用来描述多分度秤，由它确定传感器可使用的不超过最大允差的分度值。相对Y=Emax/Vmin，该比值描述与传感器容量无关的最大分辨率，即传感器使用时允许的大分度数。

(5) Relative to Dr, i.e. z = Emax (/ 2 × DR), the ratio is used to describe the multi scale scale, which determines the division value that the sensor can use and does not exceed the maximum tolerance. Relative to y = Emax / Vmin, this ratio describes the maximum resolution independent of the sensor capacity, that is, the maximum number of divisions allowed when the sensor is used.

（6）“称重传感器的分级原则，将传感器划分为明确的准确度级别，是为了便于传感器在各种质量测量系统中的应用。本规程（JJG669-2003）的使用中必须识别，一个传感器的性能可以在使用该传感器的测量系统中，通过补偿而得到改善。因此本规程既不要求传感器与使用它的称量系统具有相同的准确度级别，也不要求显示质量的称重仪表，使用获得批准的单的传感器。”不能正确认识上面的技术条件的内涵，就不可能根据传感器的技术参数，正确地设计衡器，并会对n≤nmax和v≥vmin两个制约条件，产生困惑和混乱。

(6) "The grading principle of load cells, which divides sensors into definite accuracy levels, is to facilitate the application of sensors in various quality measurement systems. It must be recognized in the application of this Regulation (jjg669-2003) that the performance of a sensor can be improved by compensation in the measurement system using the sensor. Therefore, this procedure does not require the sensor to have the same accuracy level as the weighing system in which it is used, nor does it require the use of an approved separate sensor for the weighing instrument displaying the quality. " If we can't understand the connotation of the above technical conditions correctly, we can't design the weighing instrument correctly according to the technical parameters of the sensor, which will cause confusion and confusion to the two constraints of n ≤ nmax and V ≥ Vmin.

例如，能不能用nmax=3000的传感器制作分度数较高于分度数高于3000的衡器？如何根据Z和Y值设计多分度和多量程衡器？这些问题长期以来在衡器界，都是难以得到解答的。由于在有些人的思想中对这些问题已形成了固定的思维模式，要改变起来需要有充足的说明理由。详尽的说明需要较大的篇幅，我准备另写一篇文章来详细说明。

For example, can a sensor with nmax = 3000 be used to make a weighing instrument with a division number higher than or equal to 3000? How to design multi index and multi range weighing instrument according to Z and Y values? For a long time, these problems are difficult to be solved in the weighing instrument field. Since some people have formed a fixed mode of thinking about these problems, we need to have sufficient reasons to change them. A detailed description requires a large space, and I am going to write another article to elaborate.