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ADVICE AND INSTRUCTIONS
Manual interventions in the process
When faults occur during a process because of interruptions in the
supply of media or component faults, the process may, after an alarm
has been triggered, get stuck in a phase from which the control
equipment cannot proceed.
Various options are then open to the user. Options that do not involve
a hazard to the user are described in the “Alarms” section of the
OPERATOR MANUAL. If the operator’s options for action are not
possible or do not solve the problem, a trained technician must be called
to advance the program manually.
Manual stepping with keyswitch
On manual stepping of a program with the button or the “STEP”
button after the keyswitch has been set to Stepping/Authorized user, all
parameters are controlled by the automatic control equipment, so that
hazardous situations cannot normally occur. With manual control, the
program is stepped from one process phase to another without
temperature, time or pressure conditions being met.
For safety reasons, the ability to step past critical process conditions
is blocked. This applies to certain pressure, temperature and level
conditions, except where there is a fault in an analog sensor. Stepping
should be while the unit is still in the alarm phase.
With the stepping option, a technician can under certain
circumstances manually bypass built-in safety conditions.
When using this method, the blocks that prevent
hazardous situations from arising are removed. The
technician himself has to decide which operations are
permitted.
The above method may only be used by technicians who
are thoroughly familiar with the process, the properties of
the goods and the functioning of the individual
components.
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