CiDRA GVF-100 Gas Volume Fraction Monitoring System User Manual

Page 55

Page 9-4

20639-01 Rev 03

CUR1

– These terminals are used for connection to the primary 4-

20mA output from the transmitter. The transmitter can be configured
such that an external supply can be used for power (i.e. the 4-20mA
loop current is driven externally) or such that the transmitter itself will
power the loop. A combination of power wiring and internal software
setting will ensure that the 4-20mA output will function properly. The
following figures show proper wiring for internal and external power.
The software configuration must be set to match the external wire
connections for proper operation of this output. The primary 4-20mA
output is the only 4-20mA output that supports HART communication.

CUR2

– These terminals are used for connection to the secondary 4-

20mA output from the transmitter. As with the first 4-20mA line, the
transmitter can be configured such that an external supply can be
used for power or such that the transmitter itself will power the loop. A
combination of power wiring and internal software settings will ensure
the 4-20mA output will function properly. The software configuration
must be set to match the external wire connections for proper
operation of this output.

Internally Powered 4-20mA Loop Configuration

- The hookup for a

4-20mA interface configured as “Internally Powered” is shown below.
The maximum value of R

is 500 Ohms. The voltage across R

must

be measured differentially. The V

INT

connection is tied to a –10V

reference internal to the transmitter and must not be connected to
ground in the plant control system.

Figure 47

Internally (Transmitter) Powered 4–20mA Loop

(-10v)

Plant Control System

Measure
Differentially

Do Not Tie
R

To GND

SONARtrac

Transmitter

4-20 mA
Driver

+12v

+10v