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Instrumentation of the turbine meter
The sensitivity of the Preamp rolls off as frequency increases, matching the characteristic
output of a turbine meter with inductive pickup. High sensitivity at low frequencies allows
the turbine meter to operate at its lowest possible flow rates. Reduced sensitivity at high
frequencies prevents spurious counting due to RFI and transients.
Common mode rejection
The Preamp employs a differential amplifier which responds only to differences between
the COIL+ and COIL- wires.
Dual outputs
With its dual outputs, the Preamp works with virtually any end device. One output swings
from 0V to5V regardless of the power supply voltage, and is suited for most inputs with
thresholds of 4V or less. An open collector output swings from 0V to any available power
supply voltage up to 36V, sinking up to 50 mA.
Wide Power Supply Range, Low Power Operation
The Preamp operates with any power supply voltage from 5.4 to 26V and requires less
than 1 mA. It can be added to virtually any system without special power conditioning, and
typically with no impact on power system requirements.
Bullet-Proof I/O
All field wiring terminals are protected against ESD (electrostatic discharge) and transients.
Rugged and Convenient Packaging
The Preamp is fully encapsulated in a compact package suitable for mounting on a panel or
in a standard 3" ID explosion-proof housing. Pluggable cage-clamp type connectors allow
convenient, reliable connections without the need for lugs. Terminals are labeled with
signal names to simplify installation.
Figure 3-2:
16
Universal pre-amplifier 0-5 V out configuration
"PT" Liquid Turbine Meters
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