Transmitter
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I encountered a Honeywell single-flange transmitter; after powering it on, no display was visible on the device. When the wires were disconnected, a voltage of 23V was measured at the power supply, but still no display appeared even after the wires were reconnected. The voltage measured at that time was only 13V. Initially, I thought the issue was related to the safety gate, but the problem persisted even after replacing it. The current output from the gauge was 22.7mA. I’d like to ask everyone, has anyone encountered this situation? Is it a problem with the header circuit board? There are no spare parts available for replacement at the moment, so it’s impossible to determine the cause of the problem
You can replace the header display module, or take one from another working table to test it; Honeywell transmitters often develop problems
A normal pressure transmitter or temperature transmitter can be connected first to determine whether the issue lies with the Honeywell transmitter itself
This post was last edited by cqdfwy on 2019-11-4 at 11:42. An open-circuit measurement showed a voltage of 23V, so it’s unlikely that there is a problem with the cable (cable failure can be almost ruled out; if there is a fault, it’s likely to be a minor one). When the transmitter was connected for measurement, the voltage was only 13V, which indicates that a fault in the transmitter (local short circuit) is more likely to be the cause. It can be handled in the same way as on the floor above.
{:2_45:} The pig said: 1. First, remove the safety barrier and supply power directly to the meter, to see if the meter will light up and start working. 2. It won’t turn on and start working – the gauge is broken. Well then, take it apart, Old Huo; try breaking it down to see if it can be fixed. 3. It can turn on and start working, so the gauge is fine. The reasons for this malfunction are mainly three: first, the voltage drop across the safety barrier is too high; second, the current sampling resistors in the DCS cards are too large; third, the power supply either lacks sufficient power or has too low a voltage.
First, check whether the indication of this transmitter on the indoor DCS is correct; if it is, then examine the local gauge.
It shows full scale, with a current of 22.7 mA
The manufacturer’s technician will be at the factory tomorrow; we’ll share the reasons with everyone then, hoping it will be useful to you all
The transmitter is old; when operating on 24V and delivering a current of 20mA, the load, safety barrier, and wiring consume 6–8V or more of the voltage, so the voltage at the transmitter should normally be above 15V. And the transmitter should still be able to function properly at 12V ； When the operating current required by the transmitter’s circuit is less than the signal current, various abnormalities occur. The actual output current does not match the current displayed on the meter ； It is not displayed on-site ； The output current stops increasing once it reaches a certain value. It is a typical manifestation of circuit aging (including display module aging) or soft faults. If the meter is connected directly to 24V (without a load resistor) and operates normally, it can generally be concluded that the transmitter circuit has aged. Replacing the amplifier or display module may fix the issue.
It’s most likely a transmitter issue; it’s recommended to replace it. Once it’s replaced and fixed, keep it as a spare part