DayTronic 3000 series User manual
MODEL
3178
STRAIN GAGE CONDITIONER
SB.5.1
INSTRUCTION MANUAL
3000
Instrument Series
Copyright © 1996, Daytronic Corporation. All rights reserved.
No part of this document may be reprinted, reproduced, or used in any form or by
any electronic, mechanical, or other means, including photocopying and recording,
or in any information storage and retrieval system, without permission in writing
from Daytronic Corporation. All specifications are subject to change without notice.
Correction
to Model 3178 Instruction Manual, v. SB.5.1
The I/O Wiring Data in Fig. 4 of this manual does not give the correct shield pairing of
cable wires, which is shown in the revised diagrams below and on the following page:
1
A
2
B
3
4
C
9
A
D
B
C
+EXC
–EXC
+SENSE
–SENSE
+SIG
–SIG
CAL SENSE
C
.
.
.
A
Extra Wire, paired
with CAL SENSE,
unconnected at
Connector A
SHIELD
Daytronic 400 Series
Transducer Connections
1
A
2
B
3
4
C
9
D
A
B
C
+EXC
–EXC
+SENSE
–SENSE
+SIG
–SIG
CAL SENSE
B
.
.
.
A
Extra Wire, paired
with CAL SENSE,
unconnected at
Connector A
SHIELD
Daytronic 500 Series
Transducer Connections
1
A
2
B
3
4
7
E
B
C
D
E
+EXC
–SENSE
+SIG
–SIG
LEBOW CAL
D
.
.
.
A
Extra Wire, paired
with LEBOW CAL,
unconnected at
Connector A and
at transducer
SHIELD
A
–EXC
+SENSE
Lebow 1600 Series
Rotary Transformer Torque
Transducer Connections
(cont’d)
Correction
to Model 3178 Instruction Manual, v. SB.5.1 (cont’d)
+SENSE
–EXC
–SENSE
+SIG –SIG
CAL
SENSE
1
A
2
B
3
C
4
9
.
.
.
A
SHIELD
+EXC
Daytronic 3X78 Instrument to Generalized Strain Gage Transducer
Showing CAL SENSE Connection
4-Wire Configuration for Cables
Shorter Than 20 Feet
+SENSE
–EXC
–SENSE
+SIG –SIG
CAL
SENSE
1
A
2
B
3
C
4
9
.
.
.
A
SHIELD
Extra Wire, paired with CAL SENSE,
unconnected at Connector A
+EXC
6-Wire Configuration for Cables
Shorter Than 20 Feet
+SENSE
–EXC
+SIG –SIG
CAL
SENSE
1
A
2
B
3
C
4
9
.
.
.
A
SHIELD
Extra Wire, paired with CAL SENSE,
unconnected at Connector A
–SENSE
+EXC
8-Wire Configuration for Cables
Longer Than 20 Feet
MODEL
3178
STRAIN GAGE CONDITIONER
INSTRUCTION MANUAL
Model 3178 Instruction Manual, v. SB.5.1
Pub. No. 3178M.5.1, Issued 03/01
Part No. 91121
Daytronic Corporation
Dayton, OH • Tel (800) 668-4745
www.daytronic.com
This page intentionally blank.
Daytronic Corporation
TABLE OF CONTENTS
Section Page
1
Description................................................. 1
2
Installation and Cabling...................................... 3
3
Calibration
..................................................
11
4
Block Diagram Description 14
5
Verification of Normal Operation 19
LIST OF ILLUSTRATIONS
Figure
Page
1
Model 3178 Strain Gage Conditioner 1
2
Instrument Mounting Dimensions 4
3
Instrument Panel Mounting
5
4
I/O Wiring 9
5
Front Panel Description 12
6
Block Diagram
.............................................. 17
7
Star Bridge Construction 20
LIST OF TABLES
Table
Page
1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
PLEASE NOTE: Sections 6 and 7, Figures 8 and
9, and Table 2 have been
removed from this manual.
If you need information regarding specific 3178 components and circuitry,
please contact the Daytronic Service Department at (937) 293-2566.
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Daytronic Corporation
INSTRUCTION MANUAL
MODEL 3178 STRAIN GAGE CONDITIONER
1.DESCRIPTION
The Model 3178 is a conditioner-amplifier for use with resistance strain gage
transducers in applications which require an ac excitation voltage. It supplies a 3.28
kHz
precision amplitude-regulated excitation, remotely sensed, to the transducer.
The instrument uses a phase-sensitive carrier amplifier-demodulator design so that
both direction and magnitude of the applied force are determined. The 3178 con-
tains the necessary balancing and calibration controls and conditions/amplifies the
applied input to a standard Five-Volt Data Signal Level which is the output analog
signal level of 3000 Series Instruments. Two analog outputs, having low-pass cutoff
frequencies of 2 Hz and 400 Hz, are provided. The filtered outputs provide for
averaging or smoothing of signals containing noise or other unwanted dynamic
components which are periodic in nature. Filtering removes these dynamic compo-
nents so that stable digital indication and precise jitter-free
precise jitter-free
control action can be
obtained. The Model 3178 is shown in Figure 1 and the specifications are given in
Table 1.
Figure 1. Model 3178 Strain Gage Conditioner
1
Table
1.
Specifications
Model 3178
Transducers:
4-arm bridges, 90
to
1000 ohms. nominally 0.5
mv/v
to
5
mv/v,
full scale.
Cables:
4-,
5-,
or 7-wire, depending on application; 1000
feet
maximum length.
Bridge Excitation: Regulated 3.28
kHz
ac; nominally 2
vac.
Balance Adjustments:
10-turn
coarse and fine; will balance 1.5
mv/v
initial unbalance.
Span Adjustments:
10-turn
coarse and fine; 0.5
to
5
mv/volt,
full scale.
Analog Outputs: Two
analog
outputs
available; 0
to
±5
volts
with
50%
overrange, 5 milliamperes maximum.
Bandpass
is dc to 2 Hz or dc to
400 Hz.
Active
low-pass filters provide for
rolloff
of 60
dB
per decade
above cutoff frequency. Full-scale slew time is
1.4/f
seconds, where f
is
the
cutoff frequency.
Output Ripple and Noise: 0.15% of full scale (rms) maximum for
400-Hz
output;
0.02% of full scale (rms) on
2-Hz
output.
Accuracy: 0.05% of full scale.
Dimensions: 1.7 x 4.41 x 8.5 (HWD inches).
Operating Temperature Range: 0to +130 degrees F.
Power Requirements: 105 to 135 volts
ac,
50 to 400 Hz at 5
watts
maximum.
2
Daytronic Corporation
The Model 3178 is useful in applications involving transformer coupling to the
strain gage bridge (for example, rotary transformer torque sensors) and in certain
applications that require high sensitivity with optimum signal-to-noise characteris-
tics. Carrier amplifiers offer higher sensitivity than dc amplifiers and, since they
respond only to the modulated carrier frequency, they reject certain extraneous
voltages that can cause error in dc systems. These error sources include
ther-
mocouple
or galvanic
voltages in the cable-connector system, homopolar
voltages
from rotating machinery, low-frequency
pickup, and
1/f
noises of various origin.
Consequently, the Model 3178 is an excellent instrument choice when special noise
environment conditions and the need for amplification of low-level signals exist.
Calibration of the 3178 is accomplished by the conventional shunt technique,
using an internally installed calibration resistor. Front-panel CAL buttons provide
for shunt calibration in both the positive and negative realms. An internal symmetry
control provides independent adjustment of negative realm sensitivity for trans-
ducers that do not have symmetrical slope characteristics. Positive-realm calibra-
tion can be remotely checked by means of Remote Cal terminals on the instrument
I/O connector.
The 3178 Strain Gage Conditioner is also available in two additional forms. The
Model 3278 contains a Digital Indicator to view the analog output of the conditioner.
The Model 3378 contains a Limit section (in addition to a Digital Indicator) that
provides High/OK/Low
indications and outputs. The Digital Indicator and Limit
features are standard to all 3000 Instruments and are covered in separate instruction
manuals.
2. INSTALLATION AND CABLING
The following paragraphs provide the instructions for instrument installation
and cabling.
Mounting. The 3000 Series Instruments can be operated as bench-top units or
they can be rack- or panel-mounted. Clearance dimensions for a bench-mounted
instrument are given in Figure 2. Panel cut-out dimensions for panel mounting are
also shown in Figure 2. Up to four 3000 Series Instruments can be mounted in a
19-inch
rack using the 1.75-inch high Model 3004 Rack Adaptor. Rack-mounting
dimensions are also given in Figure 2. To panel mount an instrument, proceed as
follows. Refer to Figure 3.
IMPORTANT: The unit is shipped with two spacer washers on the securing screws of the rear-panel I/O
Connector. When panel-mounting the unit, you MUST REMOVE THESE WASHERS, so that the
printed-
circuit board may move forward about
1/8" during Step (f).
3
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