Ametek PMT 40, Руководство пользователя

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User Manual
8
TUNING CONTROLLER TO PROCESS
PROPORTIONAL CONTROLLER
Start up – turn on air and drain dripwell through
its drain valve. Adjust regulator to required
supply pressure. *
Adjust set pointer to desired operating point by
turning set point knob.
Watch control operation. If controlled pressure
cycles, increase proportional band in steps until
stable. Then increase by half of setting for a
margin of stability. If control seems sluggish and
wandering, reduce proportional band setting
in steps until measurement is jittery or slightly
cyclic. Increase proportional band in steps until
stable then increase by half of setting for a margin
of stability. Increasing proportional band until
just stable is not recommended as instability
and cycling may result under slightly changed
operating conditions.
When continued adjustment does not bring
process into control it is best to look for erratic
behavior of process, control valve, or controller.
See section on TROUBLE SHOOTING. By
controlling process manually it will become
apparent whether difficulties are with control
system (instrument and valve) or with process.
See section on MANUAL CONTROL.
MANUAL RESET
After the controller is in operation, the black
indicating pointer may not be over the red setting
pointer, since factory adjustment is based on
pointers coinciding at mid-span output.** To
manually reset the pointers, note position of black
pointer then turn setting knob to move red pointer
up to that position. Allow measurement to settle.
Turn synchronization nut on the proportional
feedback (Fig. 11) to bring black pointer into
matching position. The pointers will only match
for the load at which the adjustment was made.
Where load is quite variable, synchronization is
usually omitted.
DIFFERENTIAL GAP CONTROLLER
Turn on air and drain dripwell through its drain
valve. Adjust regulator to required supply
pressure.* Set red pointer to center of desired
differential gap. Turn band adjustment to
desired band width on proportional dial. Note
extreme high and low values which process
reaches. Adjust band to widen or narrow as
necessary. Adjust red pointer up or down until
differential gap is at desired level. Red pointer
may be anywhere in the band. To set pointer for
top, bottom or center of band (as desired) hold
red pointer hub with 0.25” ignition wrench and
turn pointer, pushing it near its center to avoid
bending it.
* 20 psi (140 kPa) for 15 psi (100 kPa) output
35 psi (240 kPa) for 30 psi (200 kPa) output
65 psi (450 kPa) for 60 psi (400 kPa) output
**9 psi (60 kPa) for 3-15 psi (20-100 kPa) controllers
18 psi (125 kPa) for 6-30 psi (40-200 kPa) controllers
36 psi (250 kPa) for 12-60 psi (80-400 kPa) controllers
MULTI-MODE CONTROLLER
The output of multi-mode controllers is the
result of several actions acting simultaneously.
Since at any moment the control effects may be
additive or may be opposed, it may be difficult to
analyze process changes. In difficult applications
or in troublesome situations it is helpful to record
the measurement and the output pressure. When
recording instruments are not available, the value
of the controlled variable and output pressure
may be read periodically and plotted.
When continued adjustment per these
instructions fails to bring process into control
it is best to look for erratic behavior of the
process, control valve or controller. See section
on TROUBLE SHOOTING. By controlling the
process manually it will become apparent
whether difficulties are with the control system
(instrument and valve) or with the process. See
section on MANUAL CONTROL. Manual start
up may also be used if automatic start up causes
excessive overshooting.
TUNING PROPOR RESET
CONTROLLER
Note action of controller (reverse or direct). Set
red pointer 30% above black pointer if direct,
30% below black pointer if reverse acting.
Open reset valve fully by turning clockwise to
stop. Hold for a few seconds, then set reset dial
between 0.2 and 0.5 minutes per repeat. Set
proportional band at 50% (green pointer). Turn
on supply air. Output of controller should remain
zero. Drain dripwell through its drain valve.
Adjust regulator to required supply pressure.* Set
red pointer to coincide with black pointer. Output