SOR RF Continuous Level Transmitter - Manual (Page 12)

12/16 Form 837 (05.13) ©SOR Inc.
Troubleshooting
Symptom/Problem Possible Cause Corrective Action
Not current in the loop 1. Power supply turned off
2. Improper wiring at TB1
3. Excessive loop resistance 1. Check power supply
2. Check electrical connections,
figure 4
3. Reduce loop resistance or adjust
power supply
Zero point cannot be
set to 4.00mA at low
level 1. Fine zero incorrect
2. Probe capacitance greater
than 500pF when coarse
ZERO switch #4 is closed (all
other switches open) 1. Check calibration
2. Use smaller diameter probe or
replace bare probe w/insulated probe
or locate probe farther from the
vessel wall or consult the factory
Span point cannot be
increased to 20mA at
high level 1. Insufficient probe
capacitance
2. Excessive loop resistance
3. Incorrect calibration 1. Increase probe diameter or use
probe w/higher dielectric insulation
or locate probe closer to vessel wall
or install a stilling well or consult the
factory
2. Reduce loop resistance or adjust
power supply
3. Check calibration
Span point cannot be
decreased to 20mA at
high level 1. Low probe resistance to
ground
2. Probe capacitance greater
than 2,000pF 1. Consult the factory
2. Use a smaller diameter probe or
replace bare probe w/insulated probe
or locate the probe farther from the
vessel wall
Transmitter output is
20mA or greater when
the vessel is not full 1. Incorrect calibration
2. Probe shorted to ground
3. Material build-up on probe 1. Recalibrate
2. Replace the probe
3. Clean probe and replace or
possible misapplication, consult
the factory
Erratic transmitter
output 1. Turbulent process
2. Radio frequency
interference
3. Probe moving within the
vessel 1. Install a stilling well
2. Install RFI/EMI filters
3. Improve probe anchoring
Drifting transmitter
output 1. Process material
properties are changing
2. Probe insulation is eroded
3. Transmitter malfunction 1. Consult the factory
2. Verify probe integrity
3. Consult the factory
Non-linear output 1. Extreme material build-up
2. Non-parallel surfaces near
the probe
3. Conducting liquid in an
ungrounded vessel, eg:
fiberglass tank 1. Consult the factory
2. Mount the probe in a better
location or install a stilling well, or
install a probe with a ground rod
3. Connect earth ground to
instrument ground