ANALOG DEVICES 3B17 Service Manual

Wide Bandwidth LVDT/RVDT Input

FEATURES

Isolates, amplifies, & filters signals from 4-, 5, or 6-wire
Linear Variable Displacement Transformers (LVDTs).

Isolates, amplifies, & filters signals from Rotary Variable
Displacement Transformers (RVDT).

Provides an AC excitation voltage of 1V rms to 5V rms at
frequencies between 1 kHz and 10kHz.

Module circuitry can withstand 130v rms at the input screw­terminals.

All 3B17 series modules are mix-and-match and Hot
Swappable.

APPLICATIONS

Industrial signal amplification
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 +

3B17

FUNCTIONAL BLOCK DIAGRAM

Figure 1. 3B17 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 3B17 is a wide-bandwidth single-channel signal­conditioning module which isolates, amplifies, and filters
signals from 4-, 5-, or 6-wire Linear Variable Displacement
Transformers (LVDTs) or Rotary Variable Displacement
Transformers (RVDT). The 3B17 input module provides an AC
excitation voltage of 1V rms to 5V rms at frequencies between 1
kHz and 10 kHz. All gain and zero suppression can be user­calibrated by screwdriver adjustments through the sliding door
on the top of the module. Gain can vary over an extensive 256:1
range by adjusting a combination of a rotary switch and trim
potentiometer. Zero suppression can vary over +
center setting. The current output can be independently
adjusted over a +
3B17 is mix-and-match and hot-swappable with all 3B Series
modules, so it can be inserted or removed from any socket in
the same backplane without disrupting system power.

3B Series Custom-Ranging Program – Externally­programmable Model 3B17-00, and 3B17-D-00, enable the user
to configure a special input range, excitation voltage and
excitation frequency by using the optional plug-on AC1310
ranging card, which houses user-supplied resistors to determine

.

5% range for zero and span. In addition, the

5V from the

3B17

excitation voltage amplitude and frequency. To facilitate
selecting resistors, a Windows program, 3B-CUSTOM,
calculates resistor values based on the user-desired input/output
ranges and AC excitation.

The 3B17 input and AC excitation output terminals are
protected for up to 130V rms, protecting the computer side
from damage due to field-side over-voltage faults. The LVDT
input signal is amplified to give the high level output voltage.
The 3B17 automatically compensates for phase errors between
the primary and secondary of the LVDT or RVDT, eliminating
the need for a phase adjustment and automatically rejects any
residual quadrature voltages via a unique approach to error
compensation which uses the sum of the two secondary
winding to directly drive the demodulator. The amplitude and
frequency of the AC excitation can be factory configured to
meet custom needs (Model 3B17-Custom) or externally
configured (Models 3B17-00 and 3B17-D-00) with the optional
AC1310 plug-on custom ranging card.

.

Figure 2

Rev. 0 | Page 2 of 8

3B17 Models Available

Model Excitation Voltage Excitation Frequency Output Ranges1

3B17-00

3B17-01

3B17-02

3B17-03

3B17-04

3B17-Custom

3B17-D-00

3B17-D-01

3B17-D-02

3B17-D-03

3B17-D-04

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

3 V rms 2.5 kHz -10 V to +10 V & 0 mA to 20 mA

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

5 V rms 7.5 kHz -10 V to +10 V & 0 mA to 20 mA

1 V rms 10 kHz -10.0 V to +10 V & 0 mA to 20 mA

* * *

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

3 V rms 2.5 kHz -10 V to +10 V & 0 mA to 20 mA

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

5 V rms 7.5 kHz -10 V to +10 V & 0 mA to 20 mA

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

3B17

3B17 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description Model 3B17

Input Range

Types 4-, 5-, 6-wire LVDT or RVDT, including differential coils

Standard Range 20 mV rms to 5 V rms; See Model Table for Excitation

Custom Excitation V

Voltage (R

Current (RL = 0 to 850Ω)1

With Input Overload 40 mA, maximum

Initial @ +25°C ±0.1% Span

Nonlinearity2 ±0.05% Span

Voltage Output

Zero ±0.005% of Span/°C

Span ±0.01% of Span/°C

Current Output

Zero ±25 ppm of Span/°C

Span ±25 ppm of Reading/°C

> 2 KΩ)

L

3

Voltage and Frequency

= 1 V rms to 5 V rms

exc

V

freq. = 1 kHz to 10 kHz

exc

Output Range

-10 V to +10 V

4 mA to 20 mA or 0 mA to 20 mA

Accuracy2

Stability vs. Temperature

LVDT Excitation4

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