Calibration Of 4195Kb And Kc Series Controllers; General Calibration Instructions; Process Indicator Zero And Span; Calibration - Fisher 4195 KB Series Instruction Manual

4195KA, KB, and KC Series
200
P.B.
Pressure Span
200 2 psig
30 psig
5. If the controller is used in conjunction with a control
valve, return the control valve to service by slowly
opening the upstream and downstream manual control
valves in the pipeline. Close the manual bypass valve,
if one is used.
6. Tune the various controller actions.
Tuning proportional action: Create a load upset by
momentarily changing the set point. Check for system
cycling. If the system does not cycle, lower the propor-
tional band setting (thus raising the gain) and disturb
the system again by changing the set point. Continue
this procedure until the system cycles. At this point,
double the proportional band setting (proportional
band setting 2).
Tuning reset action: Disturb the system. If the sys-
tem does not cycle, speed up the reset by changing
the setting to a lower value (faster reset). Disturb the
system again. Continue this procedure until the sys-
tem cycles. When the system cycles, multiply the re-
set time setting by a factor of three (reset setting 3)
and slow down the reset by changing the reset setting
to the higher value. The reset is now tuned.
Tuning rate action: For a controller with rate
(4195KC Series), adjust the rate toward the higher
setting until cycling occurs. When the system cycles,
divide the rate value by a factor of three (rate setting
3) and decrease the rate by changing the setting to
the lower value. The rate is now tuned.
7. Check the stability of the recommended proportion-
al band setting by introducing a disturbance and moni-
toring the process.
8. Once stable control is attained, the process pointer
and set point indicator should be in line. If they are
aligned, return the set point to the desired value. If
they are not, readjust the set point to the desired con-
trol point and proceed with step 9.
9. If the process pointer is within 5 percent of the set
point indicator, turn the link 3 adjustment (see figure
5–13 or 5–21 for location) until the process pointer
aligns with the set point indicator. Turn the link 3 ad-
justment screw clockwise to increase the process indi-
cation or counterclockwise to decrease it. If the pro-
cess pointer is misaligned with the set point indicator
by more than 5 percent of the scale span, perform the
calibration procedures for 4195KB and KC Series con-
trollers.
4–4
Allowable Overshoot
13%
Calibration of 4195KB and KC Series
Controllers

General Calibration Instructions

If the controller has the auto/manual sta-
tion (suffix letter E), be sure the control-
ler is in the automatic mode before per-
forming calibration.
If the prestartup checks, or startup, reveal faulty con-
troller operation, perform the calibration described in
this section. These instructions are valid for either
shop or field calibration, provided that open loop condi-
tions exist. Unless otherwise noted, key numbers are
found in figure 5–24.
Do not use the gauges supplied with the controller dur-
ing calibration. Monitor process pressure, supply pres-
sure, controller output pressure, and if applicable, re-
mote set point pressure with external gauges.

Process Indicator Zero and Span

Calibration

Before starting this procedure:
Provide a regulated process pressure to the con-
troller and a means of measurement external to the
controller.
Provide a means of measuring the controller out-
put pressure by connecting the controller output to a
pressure gauge (open-loop conditions must exist).
Provide a regulated supply pressure to the controller.
Do not exceed the normal operating pressure in table
1–6.
Refer to figures 4–1 and 4–3 for adjustment locations.
Any change to the process pointer span
adjustment will require readjustment of
the process pointer zero adjustment.
1. Remove the two screws (key 6) and lift off the pro-
portional band indicator cover (key 36).
2. Set the proportional band between DIRECT and
REVERSE.
3. Apply process pressure equal to the process scale
span lower limit.
4. The process pointer should indicate the process
scale lower limit. If not, adjust the process pointer to
the process scale lower limit by loosening the zero
adjustment locking screw and turning the zero adjust-
ment screw. Tighten the zero adjustment locking
screw.
Note
Note