Impulse 8B47 - Manual

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SensorLex ™ 8B Isolated Analog Signal Conditioning Products 8B
8B47
Linearized Thermocouple Input Modules
Description
8B modules are an optimal solution for monitoring real-world process signals
and providing high level signals to a data acquisition system. Each 8B47
module isolates, filters, amplifies, and linearizes a single channel of temperature
input from a thermocouple and provides an analog voltage output.
Linearization is accomplished using a four breakpoint piecewise linear
approximation.
The 8B47 can interface to industry standard thermocouple types:
J, K, and T and has an output signal of 0 to +5V. Each module is cold-junction
compensated to correct for parasitic thermocouples formed by the
thermocouple wire and screw terminals on the mounting backpanel. Upscale
open thermocouple detect is provided by an internal pull-up resistor.
Signal filtering is accomplished with a three-pole filter optimized for time and
frequency response which provides 70dB of normal-mode-rejection at 60Hz.
One pole of this filter is on the field side of the isolation barrier for anti-aliasing,
and the other two are on the system side.
A special input circuit on the 8B47 modules provides protection against
accidental connection of power-line voltages up to 240VAC. Clamp circuits on
the I/O and power terminals protect against harmful transients.
The modules are designed for installation in Class I, Division 2 hazardous
locations and have a high level of immunity to environmental noise.
Figure 1: 8B47 Block Diagram
Features
• Interfaces to Types J, K, and T Thermocouples
• Linearizes Thermocouple Signal
• High Level Voltage Outputs
• 1500Vrms Isolation
• ANSI/IEEE C37.90.1 Transient Protection
• Input Protected to 240VAC Continuous
• 120dB CMR
• 70dB NMR at 60Hz
• Low Drift with Ambient Temperature
• Accurate CJC -40°C to +85°C
• UL Listing Pending
• Mix and Match Module Types on Backpanel
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