For a pressure range of -100~0 KPa, does it correspond to 4~20 mA or 20~4 mA?
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The crude tower used for distillation is a vacuum tower, with a pressure range of -100 to 0 KPa. Does this correspond to a current range of 4–20 mA, or 20–4 mA? Or does it not matter which range is used, as long as the field instruments are matched with the DCS? Is that enough? For example, a field transmitter with a range of 100~0 KPa corresponds to 4~20 mA; the DCS configuration also uses 100~0 KPa, with a corresponding output of 4~20 mA. If the on-site pressure range is -100~0 KPa, which corresponds to 20~4 mA, and the DCS configuration also sets it at -100~0 KPa with a corresponding range of 20~4 mA, will that work?
For 4 to 20 milliamps, pressure transducers generally output 4 to 20 milliamps, while DCs usually use the default value, which is also 4 to 20 milliamps
4mA corresponds to the zero point of the measurement, not true zero; the zero point in the range of -100 to 0 refers to -100, so the corresponding current signal is 4-20mA