Problems with pressure transmitters
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The old factory has a removed EJA pressure transmitter; its nameplate has corroded to the point where it can no longer be seen. After connecting it via 475, it shows 0.89 kp at atmospheric pressure. The instrument’s range is from -1 to 1 kp, while using 475 reveals that the sensor’s pressure range is from -10 to 10 kp. It’s not possible to communicate with it using BT200. 1. Has the zero point of this table drifted? I checked and it seems there’s no way to modify it. 2. Can a pressure transmitter detect pressures that alternate between positive and negative values? I have only been exposed to those that measure positive pressure only, or negative pressure only. Newbie seeking advice
Based on what the poster has described, this should be an absolute pressure transmitter; when measuring the atmospheric pressure, it displays that value, which is 0.89 kPa. I don’t understand what is meant by the second question. If the meson being measured remains unchanged, and the transmitter shows values that are positive one moment and negative the next, it indicates that there is a problem with the transmitter; whereas if the meson itself changes its value, showing positive and negative values from time to time, then it is correct for the transmitter to display those values.
Pressure transmitters have a range from -100 KPA to 1000 KPA, or even higher; they can measure values within this range
The sensor pressure ranges from -10 to 10 kP; this refers to the range of the core used in the transmitter at the time it was manufactured. If it shows 0.89 KPa when powered on, there are two possibilities: either it is an absolute pressure transmitter, or the transmitter is damaged and its zero point has shifted. The pressure transmitter shows positive pressure at times and negative pressure at other times; it must be broken
It’s probably zero-point drift. This is a transmitter that can measure both positive and negative pressures; the lower limit for absolute pressure transmitters is 0, so negative values are not possible.
It’s normal for the pressure transmitter’s range to be from – to +; this is quite practical. Since it has been taken apart, it’s sufficient to set the zero point. If the value remains unchanged after setting it, there’s no problem. But if it starts to fluctuate again, then the transmitter is damaged. Differential pressure transmitters tend to break down easily