
5Connecting to power supply
5.1Preparing the connection
Always keep in mind the following safety instructions:
lConnect only in the complete absence of line voltage
lIf voltage surges are expected,install overvoltage arresters
The instrument requires a operating voltage of 9…32 V DC.
Operating voltage and the digital bus signal are carried on the same
two-wire connection cable.Power is supplied via the H1power supply.
Connection is carried out with screened cable according to Fieldbus
specification.
Use cable with round cross-section.Acable outer diameter of 5…9mm
(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.
Make sure that the entire installation is carried out according to the
Fieldbus specification.In particular,make sure that the bus is
terminated with suitable terminating resistors.
With plastic housing,the NPT cable gland or the Conduit steel tube
must be screwed without grease into the threaded insert.
Max.torque for all housings see chapter "Technical data"
In the case of instrument housings with self-sealing NPT threads,it is
generally not possible to have the cable glands screwed in at the
factory.The openings for the cable glands are therefore covered with
red protective caps as transport protection.
You have to replace these protective caps with approved cable glands
before setup or cover them with suitable filler plugs.Unused cable
glands do not provide sufficient protection against moisture and must
be replaced with filler plugs.
The suitable cable glands and blind plugs come with the instrument.
Make sure that the cable screening and ground is executed according
to the Fielbus specification.If electromagnetic interference is expected
which is above the test values of EN 61326-1for industrial areas,we
recommend to connect the cable screen on both ends to ground
potential.
With 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).
Safety instructions
Voltage supply
Connection cable
Cable gland ½NPT
Cable screening and
grounding
16 POINTRAC 31 •Foundation Fieldbus
5Connecting to power supply
41779-EN-120329