VEGA VEGADIF 65 4 … 20 mA_HART - Manual (Page 33)

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5 Connecting to power supply
VEGADIF 65 • 4 … 20 mA/HART
36128-EN-130417
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
Tip:
We recommend using VEGA overvoltage arresters B63-48 and
ÜSB 62-36G.X.
In hazardous areas you must take note of the respective regulations,
conformity and type approval certificates of the sensors and power
supply units.
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 EN 61140 VDE 0140-1. The VEGA
power supply units VEGATRENN 149A Ex, VEGASTAB 690 as well
as all VEGAMETs and VEGASCANs meet this requirement.
Information:
The signal conditioning instruments VEGAMET 624 and 625 as well
as VEGASCAN 693 have a digital sensor recognition. When con-
necting VEGADIF 65, a software version from 1.92 is required with
the signal conditioning instrument. For software update move under
"www.vega.com/downloads" to "Software".
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 for industrial areas, screened cable should
be used.
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.
We generally recommend the use of screened cable for HART multi-
drop mode.
Safety instructions
Voltage supply
Connection cable