Emerson Fisher KC Series Instruction Manual page 46

4195KA, KB, KC, and KS Controllers
Fault
1. Process wanders or cycles
about set point
2. Controlling off set point as
reflected by process and set point
indicators.
Note: Some offset is inherent with
proportional-only controllers
(4195KA Series). The amount of
offset is a function of the
proportional band setting
6-2
Table 6-1. Troubleshooting Chart
Possible Cause
1.1 Proportional band and reset
settings
1.2 Supply pressure varying
1.3 Process pointer rubbing on
cover or scale
1.4 Input element failure
1.5 Linkage failure
1.6 Relay malfunction
1.7 Anti-reset windup differential
relief valve set too low (suffix letter
F only)
2.1 Supply pressure not set
correctly
2.2 Flapper not aligned
2.3 Leak in input element/tubing
assembly
2.4 Indicators out of calibration
2.5 Linkage not connected
correctly
2.6 Leak in feedback system
Check
1.1 Refer to the startup procedures
for controller settings
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
1.3 Note if the pointer is bent
1.4 Inspect the element for loose
screws and damaged flexures,
links or pivots. Using a soap
solution, check the sensing
element for leaks
1.5 Check for links that are bent or
not connected properly, flexures
bent or broken, pivots broken
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.
1.7 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
2.1 Check with an external source
2.2 Refer to the flapper alignment
procedure
2.3 Using soap solution, check the
input element and tubing for leaks
2.4 Refer to the process indicator
(and remote set if applicable) zero
and span calibration procedures in
this manual
2.5 Inspect for loose screws and
damaged flexures, links or pivots
2.6 Open the reset valve to 0.1
minute/repeat. Adjust output
pressure to 1.4 bar (20 psig). Using
soap solution, check for leaks in
the proportional and reset bellows
in the tubing that connects these
bellows
(continued)
Instruction Manual
Form 5207
April 2007
Correction
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 Correct as necessary. One
regulator per instrument is
recommended
1.3 Bend pointer to provide
clearance
1.4 Repair or replace parts as
necessary
1.5 Replace or repair as necessary
1.6 If the output changes quickly in
one direction and sluggishly in the
other, replace the relay
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
2.1 Reset the supply pressure if
necessary. If the condition occurs
again, the regulator should be
rebuilt or replaced
2.2 Align the flapper as necessary
2.3 Repair or replace parts as
necessary
2.4 Adjust as necessary
2.5 Repair or replace parts as
necessary
2.6 Repair as necessary