VEGA VEGAPULS 45 4 … 20 mA; HART compact sensor - Manual (Page 38)

38 VEGAPULS 42, 44 and 45 – 4 … 20 mA
2
4 … 20 mA
2
2
4
- +
Measuring system with VEGAPULS 42 or 44 via separator (Smart-Transmit-
ter) on passive PLC (Ex ia)
• Two-wire technology (loop powered), intrinsically safe ia supply via the signal cable of the
separator for operation of the sensor in Ex zone 1 or Ex zone 0.
• Output signal sensor 4 … 20 mA passive.
• Output signal separator 4 … 20 mA active
• Optional external indicating instrument with analogue and digital display (can be mounted
up to 25 m away from the sensor).
• Adjustment with PC, HART ® handheld or adjustment module MINICOM (can be plugged into
the sensor or into the external indicating instrument VEGADIS 50).
Electrical connection
(active) 2)
VEGA-
CONNECT 2
Separator (e.g. VEGATRENN 149 Ex see
"7.2 Approvals“)
VEGADIS 50
1 )
PLC (passive) 3)
Ex area Non Ex area
1) If the resistance of the processing systems
connected to the 4 … 20 mA signal output is less
than 250
Ω, a resistor must be connected to the
connection cable during adjustment to get a loop
resistance of 250
Ω.
The digital adjustment signal would otherwise be
severely damped or short-circuited due to
insufficient resistance of the connected
processing system. Digital communication with the
PC would not be ensured.
2) 4 … 20 mA active means that the separator
delivers a level-dependent current of 4 … 20 mA
The separator reacts electrically to the PLC like a
current source.
3) 4 … 20 mA passive means that the PLC consumes
a level-dependent current of 4 … 20 mA. The PLC
reacts electrically like a varying resistor
(consumer).
HART ® handheld
Zone 0
or Zone
1
EEx ia