Fisher 2502 Series Level-Trol Instruction Manual page 18

2502 Series
Fault
1. Process wanders or cycles
around setpoint.
2. Controller controlling off setpoint
or switching point.
3. Controller cannot attain full
output range.
4. Controller remains at full or zero
output pressure.
Perform step 1 only if adding a heat insulator to a
unit that does not have one. Key numbers in this
step are shown in figure 14.
18
Table 3. Troubleshooting Chart for 2502 Series Controllers
Possible Cause
1.1 Proportional band or specific
gravity adjsutment incorrect or
improperly tuned control loop.
1.2 Supply pressure varying or
incorrect supply pressure setting.
1.3 Sensor not plumb and is in
contact with sidewall or leak in
displacer.
1.4 Relay malfunction.
2.1 Supply pressure not set
correctly.
2.2 Leak in the controller loop.
2.3 Leaking displacer.
2.4 Flapper adjustment.
2.5 Process variable changed.
3.1 Supply pressure not set
correctly.
3.2 Flapper adjustment.
3.3 Process variable changed.
3.4 Relay malfunction.
3.5 Leaking controller loop.
4.1 Supply or output pressure
gauge malfunction
4.2 Flapper adjustment.
Check
1.1 Insure the prestartup
procedures are completed
correctly. Tune control loop.
1.2 Use input pressure gauge to
monitor stability. Make sure
regulator IN supply pressure is
withlin limits.
1.3 Check cage vessel and stillwell
installation, or for leaking displacer.
1.4 Check for relay malfunction by
using the testing relay deadband
procedure
2.1 Make sure regulator supply
pressure is set correctly. Make sure
regulator IN supply pressure is
within limits.
2.2 Use soap and water to check
for internal and external leaks.
2.3 Insure the displacer is not filling
with process fluid.
2.4 Insure the flapper is not loose
on the torque tube shaft and is
centered on the nozzle.
2.5 Insure the process variable has
not changed from original
calibration settings or, displacer not
design specific gravity of process.
3.1 Make sure supply pressure is
set correctly. Make sure regulator
IN supply pressure is within limits.
3.2 Insure the flapper is not loose
on the torque tube shaft and is
centered on the nozzle.
3.3 Insure the process variable has
not changed from original
calibration settings or, from
displacer design specific gravity.
3.4 Check for relay malfunction by
using the testing relay deadband
procedure.
3.5 Use soap and water to check
for internal and external leaks.
4.1 Insure the pressure gauges are
registering correctly.
4.2 Insure the flapper is not loose
on the torque tube shaft. Insure the
flapper is centered on the nozzle.
1. To install the heat insulator, secure the shaft exten-
sion (key 37) to the torque tube assembly rotary shaft
with the shaft coupling (key 36). Tighten both set
screws (key 38), with the coupling centered as shown
Correction
1.1 If stable control cannot be
attained and all other elements are
functionally correct, examine other
ossible causes related to the
controller/transmitter.
1.2 Apply correct supply pressure.
It is recommended to use one
regulator per instrument.
1.3 Make sure the displacer and
displacer rod hangs freely. Make
sure linkage is tight. Replace
displacer if leaking.
1.4 Depress plunger to clean out
the fixed restriction. Replace or
repair relay using the procedure in
the Maintenance section.
2.1 Reset the supply regulator
pressure. If the condition occurs
again, rebuilld or replace regulator .
Provide a regulator input pressure
within regulator limits.
2.2 Replace or repair leaking parts
as necessary.
2.3 Refer to sensor maintenance
procedures in the appropriate
sensor instruction manual.
2.4 Replace or tighten flapper
assembly as necessary and/or
center flapper on nozzle.
2.5 Change process variable back
to original sepcification or
recalibrate. If necessary, provide
replacement displacer of correct
size and recalibrate.
3.1 Reset the regulator pressure. If
problem reoccurs, replace or
rebuild the regulator. Insure
regulator IN supply pressure is
within limits at all operating levels.
3.2 Replace or tighten flapper
assembly as necessary and/or
center flapper on nozzle.
3.3 Change process variable back
to original specificaton or
recalibrate. If necessary, provide
replacement displacer of correct
size and recalibrate.
3.4 Depress plunger to clean out
the fixed restriction. Replace or
repair relay using the procedure in
the Maintenance section.
3.5 Replace or repair leaking parts
as necessary.
4.1 Replace pressure gauges. Use
corrective action given in section 3
of this table.
4.2 Replace or tighten flapper
assembly as necesary and/or
center flapper on nozzle.