Fisher 4195 KB Series - Troubleshooting Chart - Controller Off-Set and No Reset Action; Troubleshooting Chart (Continued)

4195KA, KB, and KC Series
5–2
Table 5–1. T roubleshooting Chart
Fault Possible Cause Check Correction
1. Process wanders or cycles
about set point
1.1 Proportional band and reset
settings
1.1 Refer to the startup procedures
for controller settings
1.1 If stable control cannot be
attained, and all other elements of
the loop are functionally correct,
examine other possible causes
related to the controller
1.2 Supply pressure varying
1.2 Monitor the supply pressure
with an external gauge. Ensure that
it is set correctly and does not
fluctuate. Note the number of
instruments being supplied by the
regulator
1.2 Correct as necessary. One
regulator per instrument is
recommended
1.3 Process pointer rubbing on
cover or scale
1.3 Note if the pointer is bent
1.3 Bend pointer to provide
clearance
1.4 Input element failure
1.4 Inspect the element for loose
screws and damaged flexures,
links or pivots. Using a soap
solution, check the sensing
element for leaks
1.4 Repair or replace parts as
necessary
1.5 Linkage failure
1.5 Check for links that are bent or
not connected properly, flexures
bent or broken, pivots broken
1.5 Replace or repair as necessary
1.6 Relay malfunction
1.6 By changing the process set
point and observing the output
verify that the output will change at
about the same rate in both
directions.
1.6 If the output changes quickly in
one direction and sluggishly in the
other, replace the relay
1.7 Anti-reset windup differential
relief valve set too low (suffix letter
F only)
1.7 The minimum relief valve
setting is dependent on the loop
dynamics and the controller
settings. If under normal load
changes, the relief valve opens,
instability can occur. Check by
observing the controller reaction to
a set point or load change under
closed loop conditions
1.7 If the differential relief valve
appears to be set too low, refer to
the section of this instruction
manual that covers the anti-reset
windup option
2. Controlling off set point as
reflected by process and set point
indicators.
N t S ff t i i h t ith
2.1 Supply pressure not set
correctly
2.1 Check with an external source 2.1 Reset the supply pressure if
necessary. If the condition occurs
again, the regulator should be
rebuilt or replaced
Note: Some offset is inherent with
proportional-only controllers
(4195KA Series) The amount of
2.2 Flapper not aligned
2.2 Refer to the flapper alignment
procedure
2.2 Align the flapper as necessary
(4195KA Series). The amount of
offset is a function of the
p
ro
p
ortional band settin
g
2.3 Leak in input element/tubing
assembly
2.3 Using soap solution, check the
input element and tubing for leaks
2.3 Repair or replace parts as
necessary
propor
ti
ona
l
b
an
d
se
tti
ng
2.4 Indicators out of calibration
2.4 Refer to the process indicator
(and remote set if applicable) zero
and span calibration procedures in
this manual
2.4 Adjust as necessary
2.5 Linkage not connected
correctly
2.5 Inspect for loose screws and
damaged flexures, links or pivots
2.5 Repair or replace parts as
necessary
2.6 Leak in feedback system
2.6 Open the reset valve to 0.1
minute/repeat. Adjust output
pressure to 20 psig (1.4 bar). Using
soap solution, check for leaks in
the proportional and reset bellows
in the tubing that connects these
bellows
2.6 Repair as necessary
(continued)