9
.
3
S
etup
T
he prevailing plant conditions in
fl
uence the safety of the
measuring system
.
T
herefore note the mounting and installa
-
tion instructions of the appropriate operating instructions
manual
.
M
ainly important is the correct setting of the mode
(
min
./
max
.).
9
.
4
R
eaction during operation and in case of
failure
l
T
he adjustment elements must not be modi
fi
ed during
operation
.
l
I
n case of modi
fi
cations during operation
,
you have to take
note of the safety functions
.
l
O
ccurring fault signals are described in the appropriate
operating instructions manual
.
l
I
n 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
.
l
T
he manufacturer must be informed if due to a determined
fault
,
the instrument will be exchanged
(
incl
.
a fault
description
)
9
.
5
R
ecurring function test
T
he recurring function test serves to reveal potential danger
-
ous errors that are otherwise not discernible
.
T
he function of
the measuring system must be checked at adequate intervals
.
T
he operator is responsible for choosing the type of test and
the intervals in the stated time frame
.
T
he time frame depends
on the
PFD
avg
value acc
.
to the chart and diagram in section
"
S
afety
-
related characteristics
"
.
W
ith high demand rate
,
a recurring function test is not
requested in
IEC
61508
.
T
he function of the measuring system
is proven by the frequent use of the system
.
I
n double channel
architectures it is useful to proof the redundancy by recurring
function tests in appropriate intervals
.
T
he test must be carried out in a way that veri
fi
es the
fl
awless
operation of the safety functions in conjunction with all system
components
.
M
ounting and installation
28
SU
501
E
x
-
S
ignal conditioning instrument
F
unctional safety
27953
-
EN
-
050616
