Troubleshooting; Troubleshooting Guide - Flowserve Logix 520MD+ User Instructions

19 TROUBLESHOOTING

19.1 Troubleshooting Guide

Table 27: Troubleshooting Guide
Failure
No LED is blinking
Erratic communications
Unit does not respond to analog
commands.
Valve position reading is not
what is expected.
Position is driven fully open or
closed and will not respond to
command.
Sticking or hunting operation of
the positioner
LCD backlight flickering or dim.
Logix 520MD+ and 510+ Digital Positioners FCD LGENIM0105-15-AQ – 05/16
®
Probable Cause
1. Current source too low.
2. Voltage of current source is too low.
3. Incorrect wiring polarity.
1. Current source bandwidth not limited to 25Hz.
2. Maximum cable length or cable impedance exceeded.
3. HART modem connected to PC RS-232 port not
receiving enough power
4. Interference with I.S. barrier.
5. Current source stripping (filtering) HART signal.
1. The positioner is in digital command mode.
2. An error occurred during calibration.
1. Stem position sensor mounting is off 180 degrees.
2. Stroke not calibrated
3. Tight shutoff MPC (Minimum position cutoff) is
active.
4. Custom characterization or soft stops are active.
1. Stroke is not calibrated.
2. Inner-loop hall sensor is not connected.
3. Wrong air action was entered in software.
4. Actuator tubing is backward.
5. Electro-pneumatic converter is malfunctioning.
6. Control parameter inner-loop offset is too high/low.
1. Contamination of the electro-pneumatic converter.
2. Control tuning parameters not correct.
3. Packing friction is high.
4. Spool valve is corroded or dirty.
1. The backlight uses any residual power not used by
other functions of the circuitry.
Corrective Action
1. Verify current source supplies at least 3,8 mA.
2. Verify voltage source supplies at least 10VDC.
3. Check wiring for correct polarity.
1. Maximum allowable current source rate of change is 924
mA per second.
2. Check cable size, length and capacitance. See Section 7
ELECTRICAL CONNECTIONS.
3. Verify laptop battery is not low.
4. Must use HART compatible I.S. barrier.
5. Use a 250Ω resistor and a 22 µF capacitor to create a
HART filter according to the following schematic.
250Ω
22 μF
Control System
1. Switch to analog command mode using the procedure
outlined in Section 9.3 Command Source Reset, use the
ValveSight DTM, or use a handheld communicator.
2. Check Status Codes. Correct calibration error. Recalibrate.
1. Reposition the sensor.
2. Perform a Stroke calibration (Quick-Cal).
3. Verify Tight Shutoff settings.
4. Verify custom characterization or soft-stop limits
1. Perform stroke calibration (Quick-Cal)
2. Verify hardware connections.
3. Check ATO (Air-to-open) and ATC (Air-to-Close) settings.
Recalibrate using Quick-Cal to apply settings.
4. Verify ATO/ATC actuator tubing.
5. Replace electro-pneumatic converter.
6. Adjust inner-loop and see if proper control resumes.
1. Check air supply for proper filtering and meeting
2. ISA specifications ISA-7.0.01.
3. Lower proportional gain settings.
4. Enable the stability DIP switch on the local interface and
recalibrate. If problem persists, adjust pressure control
window with handheld communicator or ValveSight and
recalibrate.
5. Disassemble and clean spool valve
1. Fluctuations in the LCD backlight are normal. No action
required.
HART
Comm
Device
65
flowserve.com