5
C
onnecting to power supply
5
.
1
P
reparing the connection
A
lways keep in mind the following safety instructions
:
l
C
onnect only in the complete absence of line voltage
l
I
f overvoltage surges are expected
,
overvoltage arresters should
be installed according to
P
ro
fi
bus speci
fi
cations
T
ip
:
W
e recommend
VEGA
overvoltage arrester
B
63
-
32
.
I
n hazardous areas you should take note of the appropriate regulations
,
conformity and type approval certi
fi
cates of the sensors and power
supply units
.
P
ower is supplied via a
P
ro
fi
bus
DP
/
PA
segment coupler or a
VEGALOG
571
EP
input card
.
T
he power supply range can di
ff
er
depending on the instrument version
.
T
he data for power supply are speci
fi
ed in chapter
"
T
echnical data
"
.
C
onnection is made with screened cable according to the
P
ro
fi
bus
speci
fi
cation
.
P
ower supply and digital bus signal are carried over the
same two
-
wire connection cable
.
U
se cable with round cross
-
section
.
A
cable outer diameter of
5
…
9
mm
(
0
.
2
…
0
.
35
in
)
ensures the seal e
ff
ect of the cable gland
.
I
f you are
using cable with a di
ff
erent diameter or cross
-
section
,
exchange the
seal or use a suitable cable gland
.
P
lease make sure that your installation is carried out according to the
P
ro
fi
bus speci
fi
cation
.
I
n particular
,
make sure that the termination of
the bus is done with appropriate terminating resistors
.
O
n the instrument with cable entry
½
NPT
and plastic housing there is
a metallic
½"
threaded insert moulded into the plastic housing
.
C
aution
:
N
o grease should be used when screwing the
NPT
cable gland or
steel tube into the threaded insert
.
S
tandard grease can contain
additives that corrode the connection between threaded insert and
housing
.
T
his would in
fl
uence the stability of the connection and the
tightness of the housing
.
S
afety instructions
V
oltage supply
C
onnection cable
C
able gland
½
NPT
VEGAFLEX
61
•
P
ro
fi
bus
PA
17
5
C
onnecting to power supply
31835
-
EN
-
100426
