
22
EB 7500 EN
Design and principle of operation
5.7.2
Type 3424-4 for bump
-
less manual/automatic
switchover
A bumpless transfer from manual to auto-
matic mode is only possible when the con-
troller output pressure yA and the manual
output pressure yH are the same. The trans-
fer from yA to yH is performed manually in
most instruments.
The Type 3424-4 Additional Module con-
nected between controller and manual con-
trol station performs this switchover automat-
ically.
The module can be equipped optionally with
a pressure limiter. This limits the controller
output pressure yA to the maximum pressure
adjusted.
5.7.3
Type 3424-5 for control
mode changeover
The control mode changeover switches the
connected controller from PI or PID to P
action if the control error exceeds an
adjustable limit. This allows a fast start-up of
the set point without overshooting.
5.7.4
Type 3424-6 for signal
limitation
The additional module is used to limit the
maximum and minimum controller output
pressure yA, the feedback signal R or the
reference variable w.
More details on Type 3424-4 Manual/auto-
matic Switchover, Type 3424-5 Control Mode
Changeover, and Type 3424-6 Signal Limiter
can be found in Data Sheet
u
T 7524.
Type 3424-5
Control Mode
Changeover
Type 3424-6
Signal Limiter
Fig. 13:
Type 3424-5 and Type 3424-6
Additional Modules
Содержание Series 420
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