If the accuracy of the instrument differs from that of the transmitter, is it the lower accuracy value that is ultimately transmitted to the DCS?

This post was last edited by 1111111 on 2018-10-29 09:27. Precision transmission: The accuracy of the instrument with the lowest precision among those used in constructing the dashboard determines the overall accuracy of the dashboard. This precision is, simply put, an estimated precision with a certain degree of likelihood. If we really want to be precise, we need to treat the dashboard as a whole with a single input and a single output, and measure it to determine the magnitude of the total error as well as its accuracy level. If the total error is 0, then the accuracy of the dashboard is not at grade 0; instead, it must be estimated based on the accuracy of the standard reference device used, either twice or three times that accuracy In terms of instrument cascading, it’s possible for 1 level + 0.5 level to equal 0.5 level, or it could equal 1.5 level; however, such situations occur very rarely, as they are extremely unlikely events. Level 1 + 0.5 level = Level 1, which is a highly likely outcome. The more instruments involved in the cascade, the higher this probability becomes, approaching 100%. When 1,000,000 level-1 instruments are cascaded together, and 4–20mA signals are transmitted across the ocean to the United States, the accuracy there is still likely to be at the level-1 standard. .

Generally, the accuracy of transmitters is higher than 100, but it is ultimately the accuracy of the instrument that matters. In practical use, various errors also have an impact, so the actual accuracy is usually lower

Under the square root: (square of the maximum error of the instrument (in absolute value) + square of the maximum error of the transmitter (in absolute value)); the result is the overall system error, that is, the instrument plus the transmitter

Thank you. May I ask where this comes from?

It comes from a textbook I used when I was in school in 1990, titled something like \"Pneumatic Instruments and Electricity Type III\" or similar； Haha, it’s too old ； Now, chapters in textbooks on the specialized subject of \"Measurement and Control\" should include methods for calculating \"systematic error\" ； I don’t have the energy to look for it. Flipping through a *Set of Questions for Instrument Technicians* will just about suffice to prove it:

This post was last edited by jlshnlhj on 2018-11-5 at 15:57. In fact, it’s at least the barrel principle.