Analog Devices B47 0 (3) Datasheet

Isolated, Linearized, Thermocouple Input

FEATURES

Interfaces, amplifies, filters, isolates, & linearizes analog
input voltages from a J, K, T, E, R, S or B-type thermocouple

Thermocouple input signal is internally linearized
High accuracy internal cold junction compensation.
Module provides +

based isolation with a common mode rejection (CMR) of 160
dB @ 50/60 Hz and a normal mode rejection (NMR) of 60 dB
@ 50/60 Hz.

All 3B47 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 single­ended 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

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

(or +

1500 V peak of galvanic transformer-

3B47

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 3B47 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,
accuracy of +
modules), and feature two high-level analog outputs that are
compatible with most process instrumentation. The isolated
input modules also provide +

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 system I/O connector while the current
output is available on the output screw terminals.

0.1%, low drift of +1 uV/ oC (low-level input

1500 V peak isolation.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

www.analog.com

GENERAL DESCRIPTION

The 3B47 is a single-channel isolated thermocouple signal­conditioning module which interfaces, amplifies, isolates,
protects, linearizes and filters analog input voltages from a J, K,
T, E, R, S or B-type thermocouple. The thermocouple input
signal is internally linearized to provide an output voltage which
is linear with temperature, High accuracy internal cold junction
compensation and a predictable upscale open circuit indication
provide a complete signal conditioning solution. To accurately
measure low level signals in electrically noisy environments,
+1500 V peak of galvanic transformer-based isolation with a
common mode rejection (CMR) of 160 dB @ 50/60 Hz and a
normal mode rejection (NMR) of 60 dB @ 50/60 Hz are
provided. This plug-in, mix-and-match, hot-swappable module
is easily field calibrated via front-panel zero and span
adjustments.

A chopper-stabilized low-drift input amplifier assures stable
long-term stability. At the amplifier input, a zero-scale input
voltage is subtracted from the input signal to set the zero-scale
value. For user convenience, the zero and span optionally can be
factory configured to meet custom needs (Model 3B37-

.

3B47

CUSTOM). Zero suppression can exceed 100% of the input
range. This enables suppression of a zero-scale input value
many times larger than the total span for precise expanded­scale measurements of a selection portion of an input signal.
The differential input circuit on the field side is fully floating,
eliminating the need for any input grounding. Signal isolation
by transformer coupling uses a proprietary modulation
technique for linear, stable and reliable performance. A
demodulator on the computer side of the signal transformer
recovers the original signal which is then filtered and buffered
to provide a low-noise, low-impedance output voltage.

Internal cold-junction compensation largely corrects errors
arising from parasitic thermocouples formed by thermocouple
connection to the input screw terminals, providing an accuracy

0.5oC over the +5oC to +45oC ambient temperature range.

of +
The module generates a predictable upscale signal to indicate an
open thermocouple; for a downscale response, connect a 47
MΩ, 0.25 Watt resistor across screw terminals 2 and 4 on the 3B
Series backplane.

.

Figure 2

Rev. 0 | Page 2 of 8

3B47 Models Available

Model Input Type Input Range Output Range Accuracy1

3B47-J-01

3B47-J-02
3B47-J-03
3B47-K-04
3B47-K-05
3B47-T-06
3B47-T-07
3B47-E-08
3B47-R-09
3B47-S-10
3B47-B-11

3B47-Custom

1

The CJC sensor accuracy (refer to specification table) should be added to the module accuracy when computing system accuracy.

* Custom Input/Output ranges are available. Refer to configuration guide.

Type J, K, T, E, R, S, or B * * *

Type J 0°C to +760°C (32°F to +1400°F) 0 V to +10 V 0.76°C

Type J -100°C to +300°C (-148°F to +572°F) 0 V to +10 V 0.4°C
Type J 0°C to +500°C (+32°F to +932°F) 0 V to +10 V 0.36°C
Type K 0°C to +1000°C (+32°F to +1832°F) 0 V to +10 V 1.0°C
Type K 0°C to +500°C (+32°F to +932°F) 0 V to +10 V 0.38°C
Type T -100°C to +400°C (-148°F to +752°F) 0 V to +10 V 1.1°C
Type T 0°C to +200°C (+32°F to +392°F) 0 V to +10 V 0.3°C

Type E 0°C to +1000°C (+32°F to +1832°F) 0 V to +10 V 1.5°C
Type R +500°C to +1750°C (+932°F to +3182°F) 0 V to +10 V 1.6°C
Type S +500°C to +1750°C (+932°F to +3182°F) 0 V to +10 V 1.5°C
Type B +500°C to +1800°C (+932°F to +3272°F) 0 V to +10 V 3.3°C

3B47

3B47 Specifications

(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description Model 3B47

Input Ranges

Thermocouple Types J, K, T, E, R, S, B
Standard Ranges Refer to Model Table
Custom Ranges ±5 mV to ±500 mV

Output Range1

Voltage (R
Accuracy2
Initial @ +25°C See Model Table

Voltage Output
Zero ±0.02°C/°C
Span ±25 ppm of Reading/°C

Zero and Span Adjustment Range

Cold Junction Compensation (CJC)
Initial Accuracy @ +25°C ±0.5 °C
Accuracy vs. Temperature, +5°C to +45°C ±0.5°C (±0.0125°C/°C)
Input Bias Current +15 nA
Input Resistance

Input, 0.1 Hz to 10 Hz Bandwidth 0.2 µV rms

> 2 KΩ)

L

Stability vs. Temperature

3

4

0 V to +10 V

±5% of Span

15 MΩ

Noise

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