Endress+Hauser RMA 421 Mise En Service page 49

3.2 Power supply connection
Before installing the unit please check that the power supply
-
corresponds with that shown on the unit legend plate.
When operating with a 90 .. 250 V AC unit a power isolator
-
must be situated within easy reach of the unit. This should
also be fused with at least 10 A.
Terminals L/L+ and N/L- are linked internally and can be used as support for
serial loop connection.
3.3 Loop power supply connection
The unit has a loop power supply that is galvanically isolated
from the power source. This means that external sensors can
be powered directly from the unit. The communication resistor
required for MART transmitters is already built into the unit
and can therefore be easily added into the communications
circuit. This means that communication with the unit can be
made by connecting the HART communication unit to the two
front panel mounted communication sockets at any time
without interrupting the measurement circuit.
-
+
HART
82
Internal circuit
Communication resistor
R 250
connection
®
83 81
Process transmitter
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