Isolated, Linearized RTD Input

3B34

Rev. 0

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FEATURES

Isolates, amplifies, linearizes, & protects analog input

voltages from a wide variety of two-, three- and four-wire

Resistor Temperature Detectors (RTDs).

Module provides a constant +10V bridge excitation voltage.

Module provides simultaneous precision voltage and

current outputs linear to input temperature.

RTD excitation current and three-wire lead resistance

compensation provide a complete signal conditioning

solution.

Module circuitry can withstand 220v rms at the input screw-

terminals.

All 3B34 series modules are mix-and-match and Hot

Swappable.

APPLICATIONS

Industrial signal conditioning

Industrial signal isolation

Industrial signal filtering

PRODUCT OVERVIEW

The 3B Series of Signal Conditioning I/o Subsystems provide a

low-cost, versatile method of transferring analog transducer

signals to a data acquisition, monitoring or control system

without the inherent noise, non-linearity, drift and extraneous

voltages. The modules are designed to directly accept analog

signals from Thermocouples, RTD’s, AC and DC Strain Gages,

Torque Transducers, Frequency Transducers, LVDTs, millivolt

or process current signals. The modules amplify, isolate,

linearize and convert the transducer output signals to

standardized analog inputs for high-level analog I/O

subsystems. The 3B Series Subsystem consists of a 10” relay

rack with universal mounting backplane and a family of plug-in

(up to 16 per rack) input and output signal conditioning

modules.

Eight and four channel backplanes are also available. Each

backplane incorporates screw terminals for sensor inputs and

current outputs and a 26-pin connector for high-level single-

ended voltage outputs to the user’s equipment.

The input modules feature complete signal conditioning

circuitry optimized for specific sensors or analog signals and

provide two simultaneous high-level analog outputs: 0 to +10V

(or +10V) and 4-20 mA (or 0-20 mA).

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 3B34 Functional Block Diagram

Output modules accept 0 to +10V (or +10V) single-ended

signals and provide an isolated 4-20 mA (or 0-20 mA) process

signal. All modules feature a universal pin-out and may be

readily hot-swapped under full power and interchanged without

disrupting field wiring.

The Analog Devices 3B Series Signal Conditioning Subsystem is

designed to easily handle signal conditioning problems in

measurement and control applications. Some typical uses are in

microcomputer-based data acquisition systems, programmable

controllers, analog recorders, dedicated control systems, and any

other applications where monitoring of temperature, pressure,

flow and analog signals are required. Since each input module

features two simultaneous outputs, the voltage output can be

used to provide an input to a microprocessor-based data

acquisition or control system while the current output can be

used for analog transmission, operator interface, or an analog

backup system.

Each input module is a single-channel signal conditioner which

plugs into a socket on the backplane and accepts its signal from

the input screw terminals. All input modules provide input

protection, amplification and filtering of the input signal,

modules), and feature two high-level analog outputs that are

compatible with most process instrumentation. The isolated

input modules also provide +1500 V peak isolation.

The choice of a specific 3B module depends upon the type of

input signal. Input modules are available to accept millivolt, volt,

process current, thermocouple, RTD, AC and DC strain gage,

frequency and LVDT inputs. The voltage output of each module

is available from the sysem I/O connector while the current

output is available on the output screw terminals.