Technical Bulletin – SL/SX Level Sensor Troubleshooting
UNIT: Model SL and SX Liquid Level Transmitter
Revision: 1.0 | Doc #: TS-3001
Symptoms, and their associatd corrective actions have been provided for the purpose of field troubleshooting the SL/SX Liquid Level Transmitters.
Note: As many sensors provide feedback to cooling systems, agitator controls or lockout controls be sure to properly secure all associated systems prior to performing troubleshooting.
NO CURRENT OUTPUT
- Loop may be broken – Measure voltage across LOOP(+) and LOOP(-) screws. Result should be between 12-40 VDC.
- Sensor circuitry damaged – Move LOOP(+) wire to TEST(-) screw. If output loop now works, internal sensor circuit has been damaged. Contact Anderson.
OUTPUT CURRENT STUCK BETWEEN 4 AND 20 mA
- Sensor must be in RUN mode – be sure sensor is NOT in CURRENT CAL or FIELD CAL switch positions.
- Check diaphragm for damage – dent or ding may cause output shifts beyond adjustment. Contact Anderson.
- Verify that CURRENT CAL value is correct – Section 3.3 of Service Manual.
CANNOT SET TO 4.00 mA (+/- .04 mA) USING ZERO SWITCH
- Verify that CURRENT CAL value is correct – Section 3.3 of Service Manual.
- If current value is greater than 4.00 mA, sensor is damaged. Contact Anderson.
- If current is less than 4.00 mA, follow checks in “No Current Output” section above.
SENSOR OUTPUT SIGNAL NOT STABLE – DRIFTS
- Verify that CURRENT CAL value is correct – Section 3.3 of Service Manual.
- Check diaphragm for damage – dent or ding may cause output shifts beyond adjustment. Contact Anderson.
- Check for signs of moisture / water in housing. If found, check cable entry. Must be sealed to prevent moisture entry. Cap must be tightened completely to engage gasket. Removing sensor from service – place in low humidity area with cap removed. Sensor may function correctly when dry.
- Prior to rezero, vessel must be empty and temperature stable. Recommend rezero after process and prior to CIP.
CURRENT OUTPUT VALUE INCORRECT
- Follow section 3.3 of Service Manual – Verifying Sensor Calibration. Sensor may have been adjusted improperly with product in vessel.
- If calibration does not match factory setting, calibrate as shown in Section 3.5 of Service Manual.
OUTPUT CURRENT JUMPS TO VALUE GREATER THAN 23 mA
- Follow section 3.3 of Service Manual – Verifying Sensor Calibration. Sensor may have been adjusted improperly with product in vessel.
- If calibration does not match factory setting, calibrate as shown in Section 3.5 of Service Manual.
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