30
EB 7500 EN
Maintenance
8 Maintenance
8.1 Checking the air supply
The modules of the pneumatic controllers
normally do not require any maintenance.
However, the air supply must be checked at
regular intervals.
To guarantee trouble-free operation of the
device, make sure that the supply air is al-
ways clean.
Check the air filter and separator installed in
the upstream air reducing station regularly. If
necessary, if the performance worsens, clean
or replace the appropriate filters.
If a controller module does not control prop-
erly or the output signal is missing, unscrew
the restriction with filter (7 in Fig. 2 and
Fig. 19) located on left-hand side under-
neath the comparator. It may be necessary to
unscrew and clean the filter or to replace it
(order no. 0550-0183).
In addition, all the ports have filters with
plastic rims (order no. 0550-0189) on the
back connecting plate of the devices. These
filters can be unscrewed and removed for
cleaning.
The self-seal push-on fittings of the controller
modules are also fitted with filters. They can-
not be renewed.
9 Conversion
9.1 Changing the controller
function
If a different control behavior is necessary,
for example, after modifying the plant, the
control behavior of the Type 3423 Controller
Module can be altered by converting or up-
grading components, such as adjusters, re-
strictors or a derivative amplifier.
The required parts are listed in Table 1 on
page 32.
1. Unscrew the fastening screw (6) at the
controller module and pull the module off
its self-seal push-on fittings. Lift it out of
the control station (control room or field
housing).
2. Unscrew screws (3.3) and pull off the
connecting plate (3.2) together with
square nuts and bolts from the controller
module.
3. Unscrew inside M3 hexagon socket
screws. Remove and/or install the cover
plates and adjusters as described below
depending on the version.
4.
P to PI:
Remove adjuster for operating
point (12) and replace it with Tn restric-
tor (10).
P to P/PI:
Remove adjuster for operating
point (12) and replace it with selector
switch with adjuster for operating point
(13) and Tn restrictor (10).
P to PD:
Unscrew cover plate (14.1). Re-
move formed seal (14.3) and insert two
O-rings (14.4) in its place. Fasten deriv-
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