Campbell Scientific CURS100 100 Ohm Current Shunt Terminal Input Module - Manual (Page 12)

CURS100 100 Ohm Current Shunt Terminal Input Module
transducer and everything is fine. However, if the battery voltage drops to 11
volts, a 20 mA current will leave just 9 volts for the transducer. In this case,
when the battery drops below 11 volts, the output of the transducer may be in
error.
Transducer
I
H
L
Signal
Power
11 VDC
(minimum)
Battery
– +
≥ 9 VDC 2 VDC
(Max)
FIGURE 4-3. 2-wire supply voltage
4.2 Three-Wire Transducers
A three-wire current loop transducer has the power supply connected directly
to the transducer. The voltage of the power supply is the voltage applied to the
transducer. The current output returns to power ground. Datalogger ground is
connected to sensor ground and the current output by the sensor must pass
through the resistor before going to ground.
Datalogger Transducer
I
H
L
G
+12 V
Signal
Power
Ground
FIGURE 4-4. 3-wire with datalogger power
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