When the on-site pressure transmitter has no output, we first need to determine where the problem is. Let's talk about it from several aspects below:
1. If the pressure transmitter UPB9 is used with the digital display meter, it is unreasonable to rashly believe that the pressure transmitter has no output when the digital display meter does not display. It is possible that the digital display is malfunctioning, causing the pressure transmitter to have no output.
So how to judge whether the pressure transmitter is outputting normally? It's very simple. Use a multimeter to directly measure the output of the pressure transmitter and measure whether there is 4-20mA current value. Of course, when the pressure transmitter is used in conjunction with other instruments, it is the same to measure the current with a multimeter to judge.
2. The standard power supply for the pressure transmitter is 24V. If the pressure transmitter has no output, we must consider whether there is 24V power supply or whether the 24V power supply is normal. However, if the pressure transmitter is connected with a digital display meter or other meters with 24V power supply, the pressure transmitter does not need to have 24V power again. This second point is only for pressure transmitter UPB13 used alone.
3. If there is 24V power supply and the power supply is normal, check whether the power cord is connected reversely or whether the positive and negative poles are connected incorrectly when the pressure transmitter has no output.
4. If the wiring is correct, then check whether there is a line disconnection in the entire loop or whether the meter is selected incorrectly (input impedance should be ≤250Ω) etc.
If the above inspections are normal, it is possible that the hardware of the pressure transmitter is faulty. For example, at the beginning of the on-site pressure transmitter due to a problem with the 24V power supply, the circuit board of the pressure transmitter may be burned out, resulting in no display and no output; for example, the overload and pressure resistance of the selected pressure transmitter are inconsistent with the on-site conditions, overload pressure may also cause damage to the pressure transmitter components, and make the pressure transmitter have no output; for example, the pressure transmitter has a display meter head. If the meter head is damaged at this time, then there will be no output from the pressure transmitter. How to judge whether the meter head is damaged? Directly short-circuit the two wires of the meter head. If the short-circuit is normal, it means that the meter head is damaged.
For details, please contact Qi Huang