VEGA VEGAPULS 51K…54K 4 … 20 mA; HART compact sensor - Manual (Page 67)

VEGAPULS 51K … 54K 67
21750-EN-031222
Supplement
4 Reaction during operation and in case of failure
In case of modifications during operation, you have to take note of the safety functions. It must
be ensured that the safety-relevant parameter adjustments remain activated.
Occurring fault signals are described in the appropriate operating instructions manual.
In case of detected failures or fault signals, the entire measuring system must be switched out
of service and the process held in a safe condition by means of other measures.
5 Recurring function test
The recurring function test serves to reveal potential dangerous errors that are otherwise not
discernible.
The function of the measuring system must be checked at adequate intervals. The operator is
responsible for choosing the type of test and the intervals in the stated time frame.
The time intervals depend upon the applied PFD
avg
value acc. to the chart and diagram in the
paragraph „Safety-related characteristics“.
The test must be carried out in a way that verifies the flawless operation of the safety functions
in conjunction with all system components. This is ensured by a controlled reaching of the
response height during a filling.
If filling up to the response height is not possible, then a response of the measuring system
must be triggered by a suitable simulation of the level or the physical measuring effect. If the
proper functioning of the measuring system is otherwise discernible (exclusion of function-
restraining errors), it is also possible to carry out the test by simulating the appropriate output
signal.
If the function test proves negative, the entire measuring system must be switched out of
service and the process held in a safe condition by means of other measures.