ANALOG DEVICES 3B30 Service Manual

Isolated Voltage Input

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FEATURES

Interfaces, amplifies, & filtersanalog input voltages.
Narrow-bandwidth (3Hz) single-channel single

conditioning.
Module provides simultaneous precision voltage and

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

terminals
Current output withstands 130V rms without damage.
All 3B30 & 3B31 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
(or +

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

3B30 / 3B31

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 3B30 & 3B31 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

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GENERAL DESCRIPTION

The 3B30 & 3B31 are narrow-bandwidth (3Hz) single-channel
signal conditioning modules which amplify, isolate, filter and
protect analog input voltages and provide simultaneous
precision voltage and current outputs. Each module performs
complete signal conditioning, including isolating (+1500V peak
input-to-output and power) and protecting their computer side
outputs from damage and loss of signal integrity, and shielding
their inputs from damage from field-side over-voltage faults up
to 220V rms. The current output withstands 130V rms without
damage and interfaces user equipment through screw terminals
located on the 3B Series backplane. Each plug-in, mix-and­match, hot-swappable module is easily field calibrated via front­panel zero and span adjustments for both voltage and current
outputs.

3B Series Custom-Ranging Program – Externally­programmable Models 3B30-00 and 3B31-00, enable the user to
configure a special input range by using the optional plug-on
AC1310 ranging card, which houses user-supplied resistors to
determine zero and span. To facilitate selecting resistors, a
Windows program, 3B-CUSTOM, calculates resistor values
based on the user-desired input/output ranges.

A chopper-stabilized low-drift (+
assures stable long-term stability. At the amplifier input, a stable,
zero-scale input voltage is subtracted from the input signal to

.

1uV/oC) input amplifier

3B30 / 3B31

set the zero-scale value. Zero suppression can exceed 100% of
the input range. This is ideal fro expanded-scale applications
requiring high-resolution measurement of a selected portion of
an input signal. For users convenience, the zero and span can be
factory configured to meet custom range needs (Models 3B30­CUSTOM and 3B31-CUSTOM) or can be externally
programmed (Models 3B30-00 and 3B31-00) via user supplied
resistors inserted in the optional AC1310 plug-on ranging card.
Internal low-pass filtering with a 4Hz cutoff (-3dB) two-pole
Butterworth filter enhances both 60dB normal-mode and 160
dB common-mode rejection at 50/60 Hz, enabling accurate
measurement of small signals in high electrical noise.

Signal isolation is accomplished by transformer coupling with a
proprietary modulation technique for linear, stable and reliable
performance. The differential input circuit on the field side is
fully floating, eliminating the need for any input grounding. 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; this
output also drives a voltage-to-current (V/I) converter to
provide a simultaneous current output for interfacing versatility.

Figure 2

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3B30 and 3B31 Models Available

Model Input Range Output Ranges1

3B30-00

3B30-01

3B30-02

3B30-03

3B30-Custom

3B31-00

3B31-01

3B31-02

3B31-03

3B31-Custom

1

Output current range may be user programmed to 4 mA to 20 mA using jumper supplied.

2

Requires AC1310 ranging card.

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

Externally Programmable2 -10 V to +10 V & 0 mA to 20 mA

-10 mV to +10 mV -10 V to +10 V & 0 mA to 20 mA

-50 mV to +50 mV -10 V to +10 V & 0 mA to 20 mA

-100 mV to +100 mV -10 V to +10 V & 0 mA to 20 mA

* *

Externally Programmable2 -10 V to +10 V & 0 mA to 20 mA

-1 V to +1 V -10 V to +10 V & 0 mA to 20 mA

-5 V to +5 V -10 V to +10 V & 0 mA to 20 mA

-10 V to +10 V -10 V to +10 V & 0 mA to 20 mA

* -10 V to +10 V & 0 mA to 20 mA

3B30 / 3B31

3B30 and 3B31 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description Model 3B30 Model 3B31

Input Range

Standard Ranges ±10 mV to ±100 mV ±1 V to ±10 V

Custom Ranges ±5 mV to ±500 mV ±0.5 V to ±20 V

Output Range

Voltage (RL > 2 KΩ)

Current (R

Maximum Current Output Span 0 mA to 31 mA *

Initial @ +25°C ±0.1% Span *

Nonlinearity ±0.01% Span *

= 0 to 850Ω)1

L

Voltage Output

Zero ±1 µV/°C (RTI) ±25 ppm of Span/°C

Span ±25 ppm of Reading/°C *

Current Output

Zero ±25 ppm of Span/°C *

Span ±25 ppm of Reading/°C *

Zero and Span Adjustment Range4

3

±5% of Span *

-10 V to +10 V *

4 mA to 20 mA or 0 mA to 20 mA *

Accuracy

Stability vs. Temperature

2

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