9
F
unctional safety
9
.
1
G
eneral
T
his safety manual applies to the
SU
501
E
x signal
conditioning instrument
.
T
he instrument corresponds to a part
system of type
A
.
I
n combination with a vibrating level switch
,
the signal
conditioning instrument can be used as measuring system for
level detection meeting the special requirements of the safety
technology
,
e
.
g
.
l
M
ode
"
max
.
" =
A
-
mode for over
fi
ll protection
l
M
ode
"
min
.
" =
B
-
mode for dry run protection
T
he measuring system is quali
fi
ed in both modes to meet the
following requirement degree acc
.
to
IEC
61508
-
2
/
IEC
61511
:
l
SIL
2
with architecture
1
oo
1
D
(
single channel
)
l
SIL
3
with architecture
1
oo
2
D
(
double
-
channel
/
redundant
)
T
he safety function of the signal conditioning instrument is the
recognition of the meas
.
currents stated below and the
conversion into a respective switching signal on the relay
contact or the transistor output
.
T
he safe condition depends on
the mode
:
l
I
n mode
"
max
.
"
:
16
±
1
m
A
for condition
"
covered
"
l
I
n mode
"
min
.
"
:
8
±
1
m
A
for condition
"
uncovered
"
l
IEC
61508
-
1
, -
2
, -
4
-
F
unctional safety of electrical
/
electronic
/
programmable
electronic systems
l
IEC
61511
-
1
-
F
unctional safety
–
safety instrumented systems for the
process industry sector
–
P
art
1
:
F
ramework
,
de
fi
ni
-
tions
,
system
,
hardware and software requirements
T
he failure limit values for a safety function
,
depending on the
SIL
class
(
of
IEC
61508
-
1
,
7
.
6
.
2
)
S
afety integrity level
L
ow demand mode
H
igh demand mode
SIL
PFD
avg
PFH
4
>=
10
-
5
up to
<
10
-
4
>=
10
-
9
up to
<
10
-
8
3
>=
10
-
4
up to
<
10
-
3
>=
10
-
8
up to
<
10
-
7
2
>=
10
-
3
up to
<
10
-
2
>=
10
-
7
up to
<
10
-
6
1
>=
10
-
2
up to
<
10
-
1
>=
10
-
6
up to
<
10
-
5
V
alidity
A
rea of application
S
afety function
R
elevant standards
S
afety requirements
SU
501
E
x
-
S
ignal conditioning instrument
25
F
unctional safety
27953
-
EN
-
050616
