UFC 3 -430-11
14 February 2001
Controller failure
High-high ala rm
High alarm
Low alarm
Low-low alarm
4-2.1.1.5 Displays. Provide each control station with the following minimum displays.
Process reading
Set point
Output signal
Input signal
Automatic/Manual indication
Controller failure i ndication
High-high alarm
High alarm
Low alarm
Low-low alarm
4-2.1.1.6 Features. Provide the following features as a minimum.
Proportional, integral and derivative control modes
Anti-reset windup
Automatic/manual and manual/automatic bumpless transfer
Change configuration without shutting down the control loop
Display configuration data without interfering with the operation of the
controller.
4-2.1.1.7 Failure Response. Provide the following minimum actions on controller
failure.
The controller should switch to manual operation, hold its last output signal,
and send out an alarm showing controller failure if a backup controller is
not provided.
The control should automatically switch over to the backup controller and
send out an alarm showing controller failure if a backup controller is
provided.
4-2.1.1.8 Signal Interface. Digital controllers do not always have dedicated contacts
for alarms and shutdowns. If the contacts are not provided, specify a controller where
dedicated contacts for each alarm and shutdown condition can be easily added using
hardware obtainable from the controller manufacturer. Provide one set of single pole
double throw (SPDT) contacts as a minimum.
4-4
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