Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question dated 2020-09-17
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Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question from 2020-09-17: Discussion question: 238. What is zero shift of a transmitter?
It is to make the lower output limit of the transmitter correspond to the lower limit of the measurement range. Move the starting point of the measurement from zero to a certain value (positive or negative). Performing a zero-point adjustment, supplemented by further tweaks, can improve the measurement accuracy of the instrument. The adjustment amount for zero-point migration is relatively large, which can improve the measurement accuracy of the instrument.
Zero migration refers to the adjustment of the instrument’s zero point (starting point) without changing the range of measurement; in other words, it involves shifting the upper and lower limits of the instrument. The purpose of this is to eliminate the effect of a fixed pressure difference. When the starting point of measurement is zero, any change in this value to a positive number represents forward migration, while a change to a negative number represents reverse migration. This is called negative migration.
Zero migration refers to the adjustment of the instrument’s zero point (starting point) without changing the range of measurement; in other words, it involves shifting the upper and lower limits of the instrument. The purpose of this is to eliminate the effect of a fixed pressure difference. When the starting point of measurement is zero, any change in this value to a positive number represents forward migration, while a change to a negative number represents reverse migration. This is called negative migration.
It is to make the lower output limit of the transmitter correspond to the lower limit of the measurement range. Move the starting point of the measurement from zero to a certain value (positive or negative). Performing a zero-point adjustment, supplemented by further tweaks, can improve the measurement accuracy of the instrument. The adjustment amount for zero-point migration is relatively large, which can improve the measurement accuracy of the instrument.
This post was last edited by Ku Liang Zhi Le on 2020-9-17 at 10:03. Keeping the transmitter’s range unchanged and moving its zero point to a certain position is what is referred to as zero point shifting of the transmitter. Before zero-point migration, if the transmitter input is zero then its output is also zero, which indicates that no migration has taken place ； If the transmitter input is negative, the corresponding output signal is at zero level; this is referred to as negative drift ； If a positive input to the transmitter results in a zero output signal, this is referred to as positive drift. Transmitter relocation is common in situations where differential pressure is used for level measurement, as the installation location of most differential pressure level transmitters is not at the level zero point.
Zero-point migration: Adjusts the lower limit value ymia of the transmitter’s output signal to correspond to the lower limit value xmin of the measurement range; when xmin=0, this is referred to as zero-point adjustment； When xmin≠0. Zero shift is the adjustment of the starting point of measurement from zero to a certain value (a positive value indicates a positive shift, while a negative value indicates a negative shift). Zero adjustment sets the starting point of measurement for the transmitter at zero.
Zero migration refers to the adjustment of the instrument’s zero point (starting point) without changing the range of measurement; in other words, it involves shifting the upper and lower limits of the instrument. The purpose of this is to eliminate the effect of a fixed pressure difference. When the starting point of measurement is zero, any change in this value to a positive number represents forward migration, while a change to a negative number represents reverse migration. This is called negative migration.
Zero migration refers to the adjustment of the instrument’s zero point (starting point) without changing the range of measurement; in other words, it involves shifting the upper and lower limits of the instrument. The purpose of this is to eliminate the effect of a fixed pressure difference. When the starting point of measurement is zero, any change in this value to a positive number represents forward migration, while a change to a negative number represents reverse migration. This is called negative migration.
Zero migration refers to the adjustment of the instrument’s zero point (starting point) without changing the range of measurement; in other words, it involves shifting the upper and lower limits of the instrument. The purpose of this is to eliminate the effect of a fixed pressure difference. When the starting point of measurement is zero, any change in this value to a positive number represents forward migration, while a change to a negative number represents reverse migration. This is called negative migration.