VEGA VEGAPULS WL 61 4 … 20 mA_HART - two-wire - Manual (Page 23)

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5 Connecting to power supply
VEGAPULS WL 61 • 4 … 20 mA/HART - two-wire
38061-EN-121011
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
Power supply and current signal are carried on the same two-wire
cable. The voltage supply range can differ depending on the instru-
ment version.
The data for power supply are specified in chapter "Technical data".
Provide a reliable separation between the supply circuit and the
mains circuits according to DIN VDE 0106 part 101.
Keep in mind the following additional factors that influence the operat-
ing voltage:
•
Output voltage of the power supply unit can be lower under nomi-
nal load (with a sensor current of 20.5 mA or 22 mA in case of fault
message)
•
Influence of additional instruments in the circuit (see load values in
chapter "Technical data")
The instrument is connected with standard two-wire cable without
screen. If electromagnetic interference is expected which is above the
test values of EN 61326-1 for industrial areas, screened cable should
be used.
For instruments with housing and cable gland, 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, exchange the seal or use a suitable cable gland.
We generally recommend the use of screened cable for HART multi-
drop mode.
5.2 Wiring plan
1
2
Fig. 23: Wire assignment fix-connected connection cable
1 brown (+) and blue (-) to power supply or to the processing system
2 Shielding
5.3 Switch-on phase
After connecting the instrument to power supply or after a voltage
recurrence, the instrument carries out a self-check for approx. 30 s:
Safety instructions
Voltage supply
Connection cable
Wire assignment, con-
nection cable