WIKA DPT-10 - Manual (Page 30)

5 Connecting to power supply
5 .1 Preparing the connection
Always keep in mind the following safety instructions:
l Connect only in the complete absence of line voltage
l If overvoltage surges are expected, overvoltage arresters should
be installed according to Profibus specifications
In hazardous areas you should take note of the appropriate
regulations, conformity and type approval certificates of the sensors
and power supply units.
Power is supplied via a Profibus DP/PA segment coupler. The power
supply range can differ depending on the instrument version. The
exact range is stated in the "Technical data".
DPT 10 is connected with screened cable according to the Profibus
specification. Power supply and digital bus signal are carried over the
same two-wire connection cable.
Use cable with round cross-section. A cable outer diameter of 5 … 9 mm
(0.2 … 0.35 in) ensures the seal effect of the cable gland. If you are
using cable with a different diameter or cross-section, exchange the
seal or use a suitable cable gland.
Please make sure that your installation is carried out according to the
Profibus specification. In particular, make sure that the termination of
the bus is done with appropriate terminating resistors.
In systems with potential equalisation, connect the cable screen
directly to ground potential at the power supply unit, in the connection
box and at the sensor. The screen in the sensor must be connected
directly to the internal ground terminal. The ground terminal outside on
the housing must be connected to the potential equalisation (low
impedance).
In systems without potential equalisation, connect the cable screen
directly to ground potential at the power supply unit and at the sensor.
In the connection box or T-distributor, the screen of the short stub to
the sensor must not be connected to ground potential or to another
cable screen. The cable screens to the power supply unit and to the
next distributor must be connected to each other and also connected
to ground potential 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 interference signals remains.
The total capacitance of the cable and of all capacitors must not exceed
10 nF in Ex applications.
Note safety instructions
Take note of
safety instruc-
tions for Ex ap-
plications
Select power supply
Selecting connection
cable
Cable screening and
grounding
30 Differential pressure transmitter DPT10 - metal measuring diaphragm • Profibus PA
5 Connecting to power supply
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-EN
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