PCB Piezotronics 8120G-400A User manual

Model 8120G-400A
Strain Gage Sensor Signal Conditioner
Installation and Operating Manual
For assistance with the operation of this product,
contact PCB Piezotronics, Inc.
Toll-free: 800-828-8840
24-hour SensorLine: 716-684-0001
Fax: [phone]
E-mail: [email protected]
Web: www.pcb.com

The information contained in this document supersedes all similar information that
may be found elsewhere in this manual.
Total Customer Satisfaction – PCB
Piezotronics guarantees Total Customer
Satisfaction. If, at any time, for any
reason, you are not completely satisfied
with any PCB product, PCB will repair,
replace, or exchange it at no charge. You
may also choose to have your purchase
price refunded in lieu of the repair,
replacement, or exchange of the product.
Service – Due to the sophisticated nature
of the sensors and associated
instrumentation provided by PCB
Piezotronics, user servicing or repair is
not recommended and, if attempted, may
void the factory warranty. Routine
maintenance, such as the cleaning of
electrical connectors, housings, and
mounting surfaces with solutions and
techniques that will not harm the
physical material of construction, is
acceptable. Caution should be observed
to insure that liquids are not permitted to
migrate into devices that are not
hermetically sealed. Such devices should
only be wiped with a dampened cloth
and never submerged or have liquids
poured upon them.
Repair – In the event that equipment
becomes damaged or ceases to operate,
arrangements should be made to return
the equipment to PCB Piezotronics for
repair. User servicing or repair is not
recommended and, if attempted, may
void the factory warranty.
Calibration – Routine calibration of
sensors and associated instrumentation is
recommended as this helps build
confidence in measurement accuracy and
acquired data. Equipment calibration
cycles are typically established by the
users own quality regimen. When in
doubt about a calibration cycle, a good
“rule of thumb” is to recalibrate on an
annual basis. It is also good practice to
recalibrate after exposure to any severe
temperature extreme, shock, load, or
other environmental influence, or prior
to any critical test.
PCB Piezotronics maintains an ISO-
9001 certified metrology laboratory and
offers calibration services, which are
accredited by A2LA to ISO/IEC 17025,
with full traceablility to N.I.S.T. In
addition to the normally supplied
calibration, special testing is also
available, such as: sensitivity at elevated
or cryogenic temperatures, phase
response, extended high or low
frequency response, extended range, leak
testing, hydrostatic pressure testing, and
others. For information on standard
recalibration services or special testing,
contact your local PCB Piezotronics
distributor, sales representative, or
factory customer service representative.
Returning Equipment – Following
these procedures will insure that your
returned materials are handled in the
most expedient manner. Before returning
any equipment to PCB Piezotronics,
contact your local distributor, sales
representative, or factory customer
service representative to obtain a Return
Warranty, Service, Repair, and
Return Policies and Instructions

Materials Authorization (RMA)
Number. This RMA number should be
clearly marked on the outside of all
package(s) and on the packing list(s)
accompanying the shipment. A detailed
account of the nature of the problem(s)
being experienced with the equipment
should also be included inside the
package(s) containing any returned
materials.
A Purchase Order, included with the
returned materials, will expedite the
turn-around of serviced equipment. It is
recommended to include authorization
on the Purchase Order for PCB to
proceed with any repairs, as long as they
do not exceed 50% of the replacement
cost of the returned item(s). PCB will
provide a price quotation or replacement
recommendation for any item whose
repair costs would exceed 50% of
replacement cost, or any item that is not
economically feasible to repair. For
routine calibration services, the Purchase
Order should include authorization to
proceed and return at current pricing,
which can be obtained from a factory
customer service representative.
Warranty – All equipment and repair
services provided by PCB Piezotronics,
Inc. are covered by a limited warranty
against defective material and
workmanship for a period of one year
from date of original purchase. Contact
PCB for a complete statement of our
warranty. Expendable items, such as
batteries and mounting hardware, are not
covered by warranty. Mechanical
damage to equipment due to improper
use is not covered by warranty.
Electronic circuitry failure caused by the
introduction of unregulated or improper
excitation power or electrostatic
discharge is not covered by warranty.
Contact Information – International
customers should direct all inquiries to
their local distributor or sales office. A
complete list of distributors and offices
can be found at www.pcb.com.
Customers within the United States may
contact their local sales representative or
a factory customer service
representative. A complete list of sales
representatives can be found at
www.pcb.com. Toll-free telephone
numbers for a factory customer service
representative, in the division
responsible for this product, can be
found on the title page at the front of this
manual. Our ship to address and general
contact numbers are:
PCB Piezotronics, Inc.
3425 Walden Ave.
Depew, NY 14043 USA
Toll-free: [phone]
24-hour SensorLineSM: [phone]
Website: www.pcb.com
E-mail: [email protected]
DOCUMENT NUMBER: 21354
DOCUMENT REVISION: B
ECN: 17900

i
Table of Contents
Section 1.0 Description Page 1
Section 2.0 Installation and Cabling Page 1
Section 3.0 Calibration Page 7
Section 4.0 Calibration of PCB Rotary Transformer Torque Sensors Page 8
Section 5.0 Troubleshooting Page 9
Reference Figures
Figure 1 Bench Mounting Clearance Dimensions Page 2
Figure 2 Panel Mounting Cut-Out Dimensions Page 2
Figure 3 Panel Mount Assembly Page 3
Figure 4 Rack Mounting Dimensions Page 4
Figure 5 4200 Series Cabling Page 5
Figure 6 182-015A Connector Pin-Out Page 5
Figure 7 4-Conductor Cabling Page 5
Figure 8 4100 Series Cabling Page 5
Figure 9 8-Conductor Cabling Page 5
Figure 10 Remote Calibration Methods Page 6
Figure 11 Master / Slave Connections Page 6
Figure 12 Front Panel Descriptions Page 11
Figure 13 Rear Panel Descriptions Page 12
MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
MANUAL NUMBER: 18222
REVISION: B
ECO NUMBER: 37012

MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
1.0 DESCRIPTION
Model 8120-400A Transducer Signal
Conditioner/Amplifier is designed for use with
resistance strain gage transducers that require
an AC excitation-amplification source. It
supplies a 3.28 kHz frequency, precision
amplitude-regulated excitation, which is
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 8120-400A contains all
necessary balancing and calibration controls
and condition/amplify the applied input to a
standard ±5 volt DC analog output level. Two
analog outputs, both having low-pass cutoff
frequencies, one of 2 Hz and the other of 400
Hz, are provided. The filtered outputs provide
for averaging of signals containing noise or
other unwanted dynamic components that are
periodic in nature.
The 8120-400A is used in applications
involving transformer coupling of the strain
gage bridge (rotary transformer coupled torque
sensors for example), and in applications that
require a high sensitivity (amplification) with
optimum "signal to noise" characteristics.
Carrier amplifiers offer higher sensitivity than
comparable DC-excited bridge amplifiers, and
since they respond only to the modulated carrier
frequency, they reject certain extraneous
voltages that cause interference with DC-
excited bridge instruments.
Note: If you have a PCB rotary transformer
torque sensor, please refer to Section 3 of this
manual, or to either the 4100 Series Rotary
Transformer Torque Sensor Manual (PCB
Manual #18227), or the 4200 Series Rotary
Transformer Torque Sensor Manual (PCB
Manual #18228), for calibration procedures.
Calibration of the instrument is made through
conventional shunt technique, using an
internally installed calibration resistor, or an
external shunt calibration reference, such as our
Model 8113A or 8113-105A Shunt Calibration
References. Front panel calibration buttons
provide for calibration in both the positive and
negative directions. An internal symmetry
control provides independent adjustment of the
negative direction sensitivity for transducers
that do not have symmetrical positive and
negative slope characteristics. Positive
direction calibration can be checked by means
of REMOTE CAL terminals on the instrument
I/O connector.
The 8120-400A Strain Gage Conditioner is also
available in two additional forms. The 8120-
410A is similar to the 8120-400A except it also
contains a dedicated 4.5 digit LED display with
a 3Hz update rate. The resolution of the digital
display is 1:5000 (0.02% FS). The display also
has a selectable decimal point, trick count
multiplier, and a trailing inert zero. For more
information on instruments with digital display,
refer to PCB Manual #27259. The Model
8120-430A contains a Limit section (in addition
to a Digital Indicator) that provides
High/OK/Low indications and outputs. Refer to
PCB Manual #19479 for more information.
The Digital Indicator and Limit features are
standard to all 8120 Series Instruments.
2.0 INSTALLATION AND CABLING
The following paragraphs provide the
instructions for instrument installation and
cabling.
Mounting
The 8120 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 1 and
cut-out dimensions for panel mounting are
shown in Figure 2.
1

MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
Figure 1 – Bench Mounting Clearance Dimensions
Figure 2 – Panel Mounting Cut-Out Dimensions
To panel mount an instrument, proceed as follows, referring 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 (6).
1. Remove the front panel by removing the two #2-56 x 3/8” flat-head screws.
2. Remove the front bezel by removing the four #6-32 x 5/8” fillister-head screws.
3. Make the panel cut-out and drill the screw clearance holes indicated in Figure 2. The front
bezel can be used as a template to define the rectangular cut-out and locate the clearance holes.
4. Hold the instrument enclosure behind the panel and re-attach the front bezel to the enclosure
from the front of the panel with the four remaining screws.
5. Reinstall the front panel.
2

MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
6. Tighten the two securing screws of the rear panel I/O connector to ensure that the connector is
seated and that the conditioner printed-circuit board is pushed fully forward so that the front-
panel screwdriver adjustments and buttons are accessible. These screws give approximately 1/8
inch adjustment; consequently, this is the maximum panel thickness that should be used.
Caution: Do not over tighten the connector securing screws or resultant damage may occur to the
printed-circuit board.
8120 SERIES
MODULE
Figure 3 – Panel Mount Assembly
To rack mount an instrument, refer to Figure 4. Up to four 8120 Series Instruments can be mounted in a
19-inch rack using the 1.75-inch high Model 8171A Rack Adaptor.
3

MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
Figure 4 – Rack Mounting Dimensions
AC Power Connection
To protect operating personnel, the 8120 Series
Instruments are equipped with a three-
conductor power cord. When the cord is
plugged into the appropriate receptacle, the
instrument is grounded. The offset pin on the
power cord is ground. To maintain the safety
ground when operating the unit from a two-
contact outlet, use a three-prong to two-prong
adaptor and connect the green pigtail on the
adaptor to ground.
To prepare the instrument for operation,
connect the power cable to a 105-135 volt AC,
50-400 Hz power source. The instrument can
use up to 5 watts of power.
Calibration Resistor
If a fixed resistor is shunted across one arm of a
strain gage Wheatstone Bridge, it produces an
unbalance equivalent to that of a particular
value of mechanical input. If this Equivalent
Input value is accurately known, it can be used
as a reference point for shunt calibration of the
system. Upon completion of installation of the
transducer and its associated cabling, the user
can:
1. Perform an overall dead weight calibration
using a precisely known value of
mechanical input. Shunt calibration data
then can be collected by means of the
installed calibration resistor for
convenience in subsequent checking.
2. Replace the installed calibration resistor
with one (or an equivalent resistance value)
supplied by the transducer manufacturer to
achieve a precisely known Equivalent Input
allowing the instrument sensitivity to be
adjusted correctly.
3. Determine the Equivalent Input value for
the installed calibration resistor, knowing
the transducer sensitivity, and adjust the
instrument sensitivity accordingly.
4. A precision 59KΩcalibration resistor is
installed in the 8120 at the factory. The
installed resistor can usually be used even
though the transducer calibration data
mentions some other resistance value. In
Section 3 of this manual, the techniques
described above are demonstrated. If,
however, the installed value of calibration
resistor is not appropriate for the transducer
and measurement range to be used, the
59KΩresistor should be replaced at this
time. The calibration resistor is mounted
on solder terminals located at the front edge
of the conditioner printed-circuit board in
the instrument. It can be accessed by
removing the front panel.
Note: PCB 4200 Series Rotary Transformer
Torque Transducers are supplied with the
appropriate calibration resistor integral to the
transducer. When this type of transducer is
used with the 8120-400A, it is not necessary to
remove the 59KΩresistor internal to the
instrument. The calibration resistor can be
appropriately connected to the 8120-400A
calibration circuit via the transducer cabling.
Refer to Figure 5 and the following section.
4

MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
Figure 5 – PCB 4200 Series Cabling
Transducer Cabling
Cabling to the transducer is accomplished via
the supplied instrument I/O connector (PCB
Model 182-015A). The I/O connector pin
numbers and functions are given in Figure 6.
Rear View
PIN PIN
1 +EXCITATION A +SENSE
2 -EXCITATION B -SENSE
3 +SIGNAL INPUT C CALIBRATION SENSE
4 - SIGNAL INPUT D OSC. DISABLE
5 SIGNAL COMMON E TRANSDUCER CABLE SHIELD
6 OSC. INPUT F OSC. OUTPUT
7 NC H ANALOG OUTPUT
8 REMOTE CALIBRATION J ANALOG OUTPUT
9 OUTPUT SHIELD K NC
10 OUTPUT SIGNAL COMMON L NC
Figure 6 – 182-015A Pin Out
Transducer cabling should take the form of a 4,
6, or 8-wire cable configuration. The 4-wire
configuration, shown in Figure 7, should be
used when overall deadweight calibration is the
method used and the required cable length is
less than 20 feet.
Figure 7 – 4 Conductor Cabling
The 6-wire configuration, shown in Figure 8,
should be used when the instrument is to be
calibrated by achieving a precisely known
Equivalent Input value through the use of a
shunt calibration resistor supplied by the
transducer manufacturer and when the required
cable length is less than 20 feet.
Figure 8 – PCB 4100 Series Cabling
The 8-wire configuration, shown in Figure 9,
should be used with cable lengths longer than
20 feet since the excitation voltage is sensed
and regulated at the transducer and optimum
shunt calibration can be achieved.
Figure 9 – 8 Conductor Cabling
5

MODEL 8120-400A AC SIGNAL CONDITIONER OPERATION MANUAL
Remote Calibration Check
The instrument can be placed in the calibration
mode (positive realm only) by shorting pins 5
(Signal Common) and 8 (Remote Cal) of the
rear-panel I/O connector. Figure 10 indicates
three methods of remotely entering the
calibration mode (external switch, transistor, or
TTL source).
Figure 10 – Remote Calibration Methods
Master/Slave Connections
When more than one 8120-400A (or a
combination of AC Carrier Conditioners) is
being used in a measurement setup (instruments
are continuously mounted or the transducer
cabling is in a common conduit or raceway),
beat frequencies may be produced from the 3-
kHz oscillators used in the instruments to power
the transducer(s) excitation. To prevent beat
frequencies from occurring, one unit can be
designated the Master, and the other units can
be driven from the Master oscillator. The
remaining units are designated as Slave
instruments. To connect as Master/Slave units,
refer to Figure 11.
Figure 11 – Master/Slave Connections
6