Anderson Instrument Company

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.

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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.

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.