1. No output display on the transmitter
| Initial inspection and testing | Solutions |
| Check that the power supply is not connected backward |
Connect the correct polarity to the power supply |
| Measuring the power supply to the transmitter for 24 V DC voltage |
It must be ensured that the supply voltage to the transmitter is ≥ 12 V (intelligent) ≥ 15 V (common). If there is no voltage, the circuit should be checked for breakage and detection of secondary instrument/PLC sampling resistance (input impedance should be ≤ 250Ω) |
| If it comes with a meter head, check if the head is damaged (you can short-circuit the two wires of the head first if it is normal after short-circuiting, then the head is damaged) |
Replacement of the meter head |
| Put an ammeter in series with the 24V power circuit and check if the current is normal |
If normal then the transmitter is normal, at this point, you should check that the other instruments in the circuit are normal |
| Is the wiring loose | Connect and tighten the wires |
| Is the power supply correctly connected to the transmitter power input |
Correctly connected to the power supply terminals in accordance with the power supply requirements |
2. Transmitter output ≥ 20mA
| Initial inspection and testing | Solutions |
| Is the transmitter power supply working? | If less than 12VDC, check if there is a large load in the circuit, the input impedance of the transmitter load should be in accordance with RL≤(transmitter supply voltage – 12V)/( 0.02A) Ω |
| Does the actual pressure exceed the full-scale limit | Re-selection of the appropriate range of pressure transmitter |
| Damage to the sensor, severe overloads can sometimes damage the isolation diaphragm | Needs to be returned to the factory for overhaul |
| Is the power cable wired correctly | The power cable should be connected to the appropriate terminal block |
3. Transmitter output ≤ 4mA
| Initial inspection and testing | Solutions |
| Is the transmitter power supply working? | If less than 12VDC, check if there is a large load in the circuit, the transmitter load capacity should comply with RL ≤ (transmitter supply voltage – 12V)/( 0.02A) Ω |
| Loose wiring causes increased contact resistance, equivalent to increased load | Connected and tightened, with load in accordance with RL ≤ (transmitter supply voltage – 12V)/( 0.02A) Ω |
| whether the actual pressure exceeds the selected range of the pressure transmitter | Re-selection of the appropriate range of pressure transmitter |
| If the sensor is damaged, severe overloads can sometimes damage the isolation diaphragm | Needs to be returned to the factory for overhaul |
4. Incorrect pressure display/output signal, error
| Initial inspection and testing | Solutions |
| Is the transmitter power supply working? | If less than 12VDC, check if there is a large load in the circuit, the transmitter load capacity should comply with RL ≤ (transmitter supply voltage – 12V)/( 0.02A) Ω |
| Are the reference pressure values always correct? | Replace the same type of product, if the error is the same, test the reference pressure gauge, if the gauge accuracy is low, you need to change to another gauge with higher accuracy |
| Is the range of the secondary instrument consistent with the range of the pressure transmitter | Adjustment of the range of the secondary instrument must be consistent with the range of the pressure transmitter |
| The capacity of the transmitter load shall be in accordance with RL ≤ (transmitter supply voltage – 12V)/( 0.02A) Ω | If not, measures can be taken depending on the situation: e.g. increase the supply voltage (but it must be lower than 36VDC), reduce the load, etc. |
| Is the corresponding equipment enclosure reliably earthed |
Reliable earthing of the equipment enclosure |
| Is the site wired separately for strong and weak power | Scientific and rational wiring to avoid signal instability/errors in the transmitter caused by interference |
| Sensor diaphragms are easily deformed, overloaded, foreign bodies and hard objects can sometimes damage the isolation diaphragm |
Needs to be returned to the factory for overhaul |
| Measurement accuracy can be affected by impurities in the pipeline |
Needs to be cleaned of impurities and a strainer added before the pressure connection |