7
M
aintenance and fault recti
fi
cation
7
.
1
M
aintenance
W
hen used as directed in normal operation
,
SU
501
E
x is
completely maintenance
-
free
.
7
.
2
F
ault recti
fi
cation
SU
501
E
x o
ff
ers maximum reliability
.
N
evertheless faults can
occur during operation
.
T
hese may be caused by the following
,
e
.
g
.:
l
M
easured value of the sensor not correct
l
P
ower supply
l
I
nterference on the cables
T
he
fi
rst measures are checking the input and output signal
.
T
he procedure is described as follows
.
I
n many cases the
causes can be determined and faults can be recti
fi
ed
.
?
T
he red failure
LED
of the signal conditioning instrument
lights
l
S
ensor not connected correctly
à
M
easure the current value on the signal cable to the
sensor
I
n
E
x systems
,
make sure that the
E
x protection is not
in
fl
uenced by the measuring instruments used
.
à
F
aults on the sensor causing a current change below
2
m
A
or above
23
m
A
,
cause a fault signal on
measuring instruments
.
C
auses of malfunction
F
ault recti
fi
cation
F
ailure
20
SU
501
E
x
-
S
ignal conditioning instrument
M
aintenance and fault recti
fi
cation
27953
-
EN
-
050616
