11
5 Connecting to power supply
SU 600 • 4 … 20 mA signal conditioning instrument
30652-EN-150129
5 Connecting to power supply
5.1 Preparing the connection
Always keep in mind the following safety instructions:
•
Connect only in the complete absence of line voltage
•
If overvoltage surges are expected, overvoltage arresters should
be installed
In hazardous areas you must take note of the respective regulations,
conformity and type approval certificates of the sensors and power
supply units.
The power supply can be 20 … 253 V AC, 50/60 Hz or
20 … 253 V DC.
The voltage supply of SU 600 is connected with standard cable ac-
cording to the national installation standards.
The instrument is connected with standard two-wire cable without
screen. If electromagnetic interference is expected which is above the
test values of EN 61326 for industrial areas, screened cable should
be used.
Connect the cable screen on both ends to ground potential. In the
sensor, the screen must be connected directly to the internal ground
terminal. The ground terminal outside on the sensor housing must be
connected to the potential equalisation.
If potential equalisation currents are expected, the screen connection
on the side of SU 600 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
interference 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.
5.2 Input mode active/passive
With the function switch you can changeover between active and pas-
sive operation of the measuring data input.
•
In active mode, SU 600 provides the power for the connected sen-
sors. Power supply and measurement data are transmitted over
the same two-wire cable. This mode is provided for connection of
measuring transducers without separate voltage supply (sensors
in two-wire version).
•
In passive mode the sensors are not powered, only the measured
value is transmitted. This input is for connection of transmitters
with their own separate voltage supply (sensors in four-wire ver-
sion). The SU 600 can be also looped into the existing circuit like a
normal ammeter.
Note safety instructions
Take note of safety
instructions for Ex
applications
Select power supply
Select connection cable
Cable screening and
grounding
Select connection
cable for Ex applica-
tions
Summary of Contents for SU 600
Page 1: ...Operating Instructions SU 600 4 20 mA signal conditioning instrument Document ID 30652...
Page 30: ...30 Notes SU 600 4 20 mA signal conditioning instrument 30652 EN 150129...
Page 31: ...31 Notes SU 600 4 20 mA signal conditioning instrument 30652 EN 150129...
Page 32: ...Subject to change without notice 30652 EN 150129...