Applicable Systems
R-Series
Symptoms
The pressure transducer reading does not match the mechanical pressure gauge by more than 0.5 bar. The controller flags a sensor drift alarm.
Possible Causes
- Pressure transducer aging causing output signal drift
- Electrical noise on the transducer signal cable
- Mechanical gauge calibration error giving a false reference
Troubleshooting Steps
- Step 1: Compare the transducer reading on the controller with a calibrated external pressure gauge
If the external gauge matches, replace the transducer; if it matches the controller, replace the gauge - Step 2: Inspect the transducer cable for damage, shielding issues, or loose terminals
Repair or reroute the cable away from motor cables to reduce EMI - Step 3: If the transducer is replaced, verify the new unit matches the 4-20mA or 0-10V output specification
The controller should display pressure within 0.1 bar of the calibrated gauge after replacement
How to Reset
Reset: The sensor alarm clears automatically once the reading stabilizes within the acceptable tolerance band.
Common Replacement Parts
- Pressure transducer: 4-20mA, 0-16 bar range (Match OEM part number)
- Signal cable: Shielded twisted pair, 2-core (Keep separate from power cables)
Frequently Asked Questions
- Q: How do I know if the transducer or the gauge is wrong?
Use a third calibrated gauge as reference. The one that agrees with the third gauge is correct.
- Q: Can I run without the pressure transducer?
Most controllers have a fallback mode using the pressure switch, but efficiency and control quality are reduced.
Source: Service Manual
Category: Compressor