ONICON F-2600 - Manual (Page 36)

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F-2600 & F-2700 Vortex Flow Meter Manual 02/15 - 0808-7 / 19204 Page 36
2.6.2 4-20 mA OUTPUT CONNECTIONS
The loop powered meter has a single 4-20 mA loop. The 4-20 mA loop current is
controlled by the meter electronics. The electronics must be wired in series with the sense
resistor or current meter. The current control electronics requires at least 12 volts at the
input terminals to operate correctly.
The maximum loop resistance (load) for the current loop output is dependent upon the
supply voltage and is given in Figure 18. The 4-20 mA loop is optically isolated from the
flow meter electronics.
R
load
is the total resistance in the loop, including the wiring resistance (R
load
= R
wire
+ R
sense
).
To calculate R
max
, the maximum Rl
oad
for the loop, subtract the minimum terminal voltage
from the supply voltage and divide by the maximum loop current, 20 mA. Thus:
The maximum resistance R
load
= R
max
= (V
supply
– 12V) / 0.020 A
Figure 18. Load Resistance Versus Input Voltage