10
5 Connecting to power supply
VEGATRENN 141 •
52239-EN-210129
5 Connecting to power supply
5.1 Preparing the connection
Always keep in mind the following safety instructions:
Warning:
Connect only in the complete absence of line voltage.
•
Connect only in the complete absence of line voltage
•
If overvoltage surges are expected, overvoltage arresters should
be installed
Note:
Install a disconnecting device for the instrument which is easy to
access. The disconnecting device must be marked for the instrument
(IEC/EN 61010).
In hazardous areas you must take note of the respective regulations,
conformity and type approval certificates of the sensors and power
supply units.
The data for power supply are specified in chapter "
Technical data
".
The voltage supply of VEGATRENN 141 is connected with standard
cable according to the national installation standards.
Make sure that the cable used has the required temperature resist-
ance and fire safety for max. occurring ambient temperature
The sensors are connected with standard two-wire cable without
shielding. If electromagnetic interference is expected which is above
the test values of EN 61326 for industrial areas, shielded cable should
be used. In general, cable screening is necessary in HART multidrop
mode.
Connect the cable shielding on both ends to ground potential. In
the sensor, the shielding must be connected directly to the internal
ground terminal. The ground terminal on the outside of the sensor
housing must be connected to the potential equalisation (low imped-
ance).
If potential equalisation currents are expected, the connection on the
processing side must be made via a ceramic capacitor (e. g. 1 nF,
1500 V). The low-frequency potential equalisation currents are thus
suppressed, but the protective effect against high frequency interfer
-
ence signals remains.
Take note of the corresponding installation regulations for Ex applica-
tions. In particular, make sure that no potential equalisation currents
flow over the cable screen. In case of grounding on both sides this
can be achieved by the use of a capacitor or a separate potential
equalisation.
The instrument is equipped with communication sockets in the front
for connection of a VEGACONNECT or another HART handheld as
well as an integrated HART resistor.
Safety instructions
Safety instructions
for Ex applications
Voltage supply
Connection cable
Cable screening and
grounding
Connection cable
for Ex applications
HART communication
