Regarding the issue of too low transmission current in Fisher float level gauges.
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There is a Fisher float level gauge on site; the equipment has been in an empty-tank condition for a long time. However, the DCS system has been reporting IOP- values for this gauge, and there is no display on the gauge’s indicator. The wiring has been checked and found to be in good condition, and the voltage at the gauge’s indicator is 22.20 V, which is also normal. The current measured in the cabinet room is 1.48 mA. Could it be that the low current transmitted back by the gauge’s indicator is causing a disconnection? How should this be solved? I’m seeking advice from experts.
The header voltage is 22.20V, so the screen should light up normally. Have you tried powering it with a portable power supply that provides higher drive power?
Just take a transmitter to the site, connect the wires and see if it’s possible to light up the gauge. If it lights up, then the gauge associated with the float is damaged; if it doesn’t light up, then check the wiring and connectors, or use a signal transmitter to send a 4-20mA signal from the site to the control unit in order to determine whether there’s a problem with the signal lines. In short, use the method of elimination to figure out whether the issue lies with the gauge, the signal lines, or the control unit.