Use As Acoustic Warning System When Hazardous Statuses Are Detected; Use As Acoustic Warning System Without Test Function - Pfannenberg DS5-SIL Betriebsanleitung/Sicherheitshandbuch

4.4.2. Use as acoustic warning system when hazardous statuses are detected

When used as a warning system following the detection of hazardous statuses, the generation of an acoustic
warning signal must be assessed as a safety function. A measurement records a dangerous condition and intro-
duces the safe condition by controlling the acoustic warning system (personnel/operator is warned).
Note: The warning of people is a voluntary measure as it requires willing handling of one or more people. This
architecture only corresponds to the requirements of the European Machinery Directive if, according to state-of-
the-art technology, no constructive safety or other voluntary measure is possible to reach a safe condition.
The diagnosis can only be taken into account if there is regular, automated function checking, the minimum in-
terval of which must be in accordance with approx. ten to one hundred times the requirement rate according to
IEC/EN61508. This possibility is only available in low demand mode and is further described and evaluated in
section 4.4.2.2.
The acoustic warning system with diagnosis function is implemented as follows:
a) A measurement (input (1), logic (2)) records a dangerous condition and activates the acoustic warning
system (output (3))
b) The diagnosis (4) monitors the function of the acoustic warning system and reports OK to a superior
control system (5)
c) If an OK message takes place, then the superior control system (5) introduces the safe condition via
other measures (6).
Fig. 7 Warning system
In section 4.4.2.2 the sounder partial systems (output - position 3) and diagnosis channel (diagnosis - position
4) are evaluated. It should be noted that the sum of all PFH or PFD values must correspond to the required
safety integration level for the entire system.
4.4.2.1.
The safety function – generating a warning signal – is realised via a one-channel system (1oo1 according to
IEC/EN61508) without taking account of the diagnosis function, as also described in section 4.2.
Low and high requirement rates (low and high demand mode) can be used in the system without automatic test
function.
Evaluation for applications with high requirement rate or continuous requirement (high demand) and low require-
ment rate (low demand) without automatic test release of the monitoring equipment.
File name:085501958j_de-en-fr-it.docx
1
Recording
(Input)

Use as acoustic warning system without test function

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2
Evaluation
(Logic)
Superior
5
system
3
Output
(Output)
Diagnosis
4
(Output)
Output
6
Dessin no.: 30007-008-13j