PCB Piezotronics 357M168 User manual

Model 357M168
Charge Output Accelerometer
Installation and Operating Manual
For assistance with the operation of this product,
contact the PCB Piezotronics, Inc.
Toll-free: 716-684-0001
24-hour SensorLine: 716-684-0001
Fax: [phone]
E-mail: [email protected]
Web: www.pcb.com

Manual 21354 Rev E
ECN 50523
Repair and Maintenance
PCB guarantees Total Customer Satisfaction through its
“Lifetime Warranty Plus” on all Platinum Stock Products
sold by PCB and through its limited warranties on all other
PCB Stock, Standard and Special products. Due to the
sophisticated nature of our sensors and associated
instrumentation, field servicing and repair is not
recommended and, if attempted, will void the factory
warranty.
Beyond routine calibration and battery replacements
where applicable, our products require no user
maintenance. Clean electrical connectors, housings, and
mounting surfaces with solutions and techniques that will
not harm the material of construction. Observe caution
when using liquids near devices that are not hermetically
sealed. Such devices should only be wiped with a
dampened cloth—never saturated or submerged.
In the event that equipment becomes damaged or ceases
to operate, our Application Engineers are here to support
your troubleshooting efforts 24 hours a day, 7 days a
week. Call or email with model and serial number as well
as a brief description of the problem.
Calibration
Routine calibration of sensors and associated
instrumentation is necessary to maintain measurement
accuracy. We recommend calibrating on an annual basis,
after exposure to any extreme environmental influence,
or prior to any critical test.
PCB Piezotronics is an ISO-9001 certified company whose
calibration services are accredited by A2LA to ISO/IEC
17025, with full traceability to SI through N.I.S.T. In
addition to our standard calibration services, we also offer
specialized tests, including: sensitivity at elevated or
cryogenic temperatures, phase response, extended high
or low frequency response, extended range, leak testing,
hydrostatic pressure testing, and others. For more
information, contact your local PCB Piezotronics
distributor, sales representative, or factory customer
service representative.
Returning Equipment
If factory repair is required, our representatives will
provide you with a Return Material Authorization (RMA)
number, which we use to reference any information you
have already provided and expedite the repair process.
This number should be clearly marked on the outside of
all returned package(s) and on any packing list(s)
accompanying the shipment.
Contact Information
PCB Piezotronics, Inc.
3425 Walden Ave.
Depew, NY14043 USA
Toll-free: [phone]
24-hour SensorLine: [phone]
General inquiries: in[email protected]
Repair inquiries: [e-mail]
For a complete list of distributors, global offices and sales
representatives, visit our website, www.pcb.com.
Safety Considerations
This product is intended for use by qualified personnel
who recognize shock hazards and are familiar with the
precautions required to avoid injury. While our equipment
is designed with user safety in mind, the protection
provided by the equipment may be impaired if equipment
is used in a manner not specified by this manual.
Discontinue use and contact our 24-Hour Sensorline if:
Assistance is needed to safely operate equipment
Damage is visible or suspected
Equipment fails or malfunctions
For complete equipment ratings, refer to the enclosed
specification sheet for your product.
Definition of Terms and Symbols
The following symbols may be used in this manual:
DANGER
Indicates an immediate hazardous
situation, which, if not avoided, may
result in death or serious injury.

Manual 21354 Rev E
ECN 50523
CAUTION
Refers to hazards that could damage
the instrument.
NOTE
Indicates tips, recommendations and
important information. The notes
simplify processes and contain
additional information on particular
operating steps.
The following symbols may be found on the equipment
described in this manual:
This symbol on the unit indicates that
high voltage may be present. Use
standard safety precautions to avoid
personal contact with this voltage.
This symbol on the unit indicates that
the user should refer to the operating
instructions located in the manual.
This symbol indicates safety, earth
ground.

Manual 21354 Rev E
ECN 50523
PCB工业监视和测量设备 - 中国RoHS2公布表
PCB Industrial Monitoring and Measuring Equipment - China RoHS 2 Disclosure Table
部件名称
有害物质
铅(Pb)
汞
(Hg)
镉
(Cd)
六价铬(Cr(VI))
多溴联苯 (PBB)
多溴二苯醚(PBDE)
住房
O
O
O
O
O
O
PCB板
X
O
O
O
O
O
电气连接器
O
O
O
O
O
O
压电晶体
X
O
O
O
O
O
环氧
O
O
O
O
O
O
铁氟龙
O
O
O
O
O
O
电子
O
O
O
O
O
O
厚膜基板
O
O
X
O
O
O
电线
O
O
O
O
O
O
电缆
X
O
O
O
O
O
塑料
O
O
O
O
O
O
焊接
X
O
O
O
O
O
铜合金/黄铜
X
O
O
O
O
O
本表格依据 SJ/T 11364 的规定编制。
O：表示该有害物质在该部件所有均质材料中的含量均在 GB/T 26572 规定的限量要求以下。
X：表示该有害物质至少在该部件的某一均质材料中的含量超出 GB/T 26572 规定的限量要求。
铅是欧洲RoHS指令2011/65/ EU附件三和附件四目前由于允许的豁免。
CHINA RoHS COMPLIANCE

Manual 21354 Rev E
ECN 50523
Component Name
Hazardous Substances
Lead (Pb)
Mercury (Hg)
Cadmium (Cd)
Chromium VI
Compounds
(Cr(VI))
Polybrominated
Biphenyls (PBB)
Polybrominated
Diphenyl Ethers
(PBDE)
Housing
O
O
O
O
O
O
PCB Board
X
O
O
O
O
O
Electrical Connectors
O
O
O
O
O
O
Piezoelectric Crystals
X
O
O
O
O
O
Epoxy
O
O
O
O
O
O
Teflon
O
O
O
O
O
O
Electronics
O
O
O
O
O
O
Thick Film Substrate
O
O
X
O
O
O
Wires
O
O
O
O
O
O
Cables
X
O
O
O
O
O
Plastic
O
O
O
O
O
O
Solder
X
O
O
O
O
O
Copper Alloy/Brass
X
O
O
O
O
O
This table is prepared in accordance with the provisions of SJ/T 11364.
O: Indicates that said hazardous substance contained in all of the homogeneous materials for this part is below the limit
requirement of GB/T 26572.
X: Indicates that said hazardous substance contained in at least one of the homogeneous materials for this part is above the limit
requirement of GB/T 26572.
Lead is present due to allowed exemption in Annex III or Annex IV of the European RoHS Directive 2011/65/EU.

MANUAL: 55308
REV: A
ECO: 49582
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General
OPERATING GUIDE
for use with
PIEZOELECTRIC CHARGE MODE ACCELEROMETERS
SPECIFICATION SHEET, INSTALLATION DRAWING
AND CALIBRATION INFORMATION ENCLOSED
PCB ASSUMES NO RESPONSIBILITY FOR DAMAGE CAUSED TO THIS PRODUCT AS A RESULT OF
PROCEDURES THAT ARE INCONSISTENT WITH THIS OPERATING GUIDE.

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TABLE OF CONTENTS
OPERATING GUIDE........................................................................................................................................................... 1
PIEZOELECTRIC CHARGE MODE ACCELEROMETERS............................................................................................. 1
1.1 Cables in Explosive Atmospheres........................................................................................................................... 3
1.2 High Temperature Differential Charge Output Sensor............................................................................................ 3
2CABLING ..................................................................................................................................................................... 3
2.1 General Precautions and Considerations................................................................................................................. 3
2.1.1 Proper Cable Type and Care.......................................................................................................................... 3
2.2 Softline Cable.......................................................................................................................................................... 3
2.3 Integraral Hardline Cable........................................................................................................................................ 4
2.4 Hardline Connection Type ...................................................................................................................................... 4
2.4.1 PCB / Lemo type connector........................................................................................................................... 4
2.4.2 High Temperature 2 –pin 7/16-27 UNS connector........................................................................................ 4
2.5 In Line Differential Charge Amplifier .................................................................................................................... 4
3INSTALLATION OVERVIEW.................................................................................................................................... 4
3.1 Equipment Inspection.............................................................................................................................................. 4
3.2 Polarity Test............................................................................................................................................................ 4
3.3 Sensor Location....................................................................................................................................................... 4
3.4 Mounting Sensor..................................................................................................................................................... 5
3.5 Route Mineral Insulated Hardline Cable................................................................................................................. 6
3.5.1 Care................................................................................................................................................................ 6
3.5.2 Bend Radius................................................................................................................................................... 7
3.5.3 Clamp Cable.................................................................................................................................................. 7
4POWERING.................................................................................................................................................................. 8
4.1 Installation............................................................................................................................................................... 8
4.2 Operation................................................................................................................................................................. 8
5HIGH-TEMPERATURE OPERATION ...................................................................................................................... 8
5.1 Introduction............................................................................................................................................................. 8
5.2 Reduced Resistance at Charge Amplifier Input ...................................................................................................... 9
5.3 Solution to Reduced Resistance.............................................................................................................................. 9
5.4 Low-Frequency Response Limitations.................................................................................................................. 10
5.5 Other Precautions.................................................................................................................................................. 10
6ACCELEROMETER CALIBRATION....................................................................................................................... 11
6.1.1 SENSOR RECALIBRATION..................................................................................................................... 11
6.1.2 BACK-TO-BACK CALIBRATION THEORY.......................................................................................... 11
6.1.3 PCB CALIBRATION PROCEDURE......................................................................................................... 13

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INTRODUCTION
Congratulations on the purchase of a quality PCB
charge mode accelerometer. In order to ensure the
highest level of performance for this product, it is
imperative that you properly familiarize yourself with
the correct mounting and installation techniques
before attempting to operate this device. If, after
reading this manual, you have any additional
questions concerning this sensor or its application,
feel free to call an Application Engineer at 716-684-
0001 or the closest PCB representative.
1.1 Cables in Explosive Atmospheres
The cable lengths (Integral and Cable and Cable
Assemblies) INSTALLED IN AN EXPLOSIVE
ATMOSPHERE IS DEFINED IN THE ATEX, IECEx,
CSA, ETC. APPROVAL CERTIFICATES.
1.2 High Temperature Differential
Charge Output Sensor
Ceramic or Single crystal shear-structured
accelerometers offer high performance for precision
vibration measurements in high-temperature
environments. The use of ceramic or single crystal
sensing crystals, operating in the shear mode,
reduces erroneous output due to base strain,
thermal transients, and transverse motion.
Charge mode accelerometers output a strong, high-
impedance charge signal directly from their
piezoelectric sensing element. They do not contain
built-in signal conditioning electronics; the signal is
conditioned externally by either a laboratory-style
charge amplifier or in-line charge converter prior to
being analyzed by a readout or recording device.
The absence of built-in electronics permits
operation to elevated temperatures of 500 °F (260
°C) for most models or up to 1300 °F (700 °C) for
special applications.
These accelerometers are ideal for structural
testing, machine monitoring, and vehicular shock,
high temperature machinery and power generation
turbine and other vibration measurement tasks
where high temperatures preclude the use of
accelerometers with built-in microelectronics.
Enclosed is a Specification Sheet, which lists the
complete performance characteristics of the
particular accelerometer.
2 CABLING
2.1 General Precautions and
Considerations
2.1.1 Proper Cable Type and Care
Ascertain that you have ordered the correct cable
type. Due to the high-impedance nature of the
output signal generated by charge mode
accelerometers, several important precautionary
measures must be followed. When using soft-line
cable always use special low-noise PCB Series
045 Low-Noise Cable (or equivalent) for
connecting to the input of the differential charge-
output accelerometers. For extremely high
temperature charge mode applications use mineral
insulated (MI) hard-line.
Care and attention to installation is essential, as
the reliability and accuracy of your system is no
better than that of the output cable. Cables and
connectors must be kept clean and dry to maintain
high insulation resistance and low frequency
responce. In the event that the insulation
resistance is compromised, inspect, clean, and
bake cables and connectors to restore insulation
resistance.
2.2 Softline Cable
Special high temperature low-noise, shielded cable
2-wire cable assembly is required with charge
mode sensors for applications up to 500°F to
connect the transducer to the charge amp. When
additional mechanical protection is required a
stainless steel armor can be used.
The shield acts as a Faraday cage to reduce
electrical noise from corrupting the signals, and
minimizes capacitively coupled noise from other
electrical sources.
Standard, two-wire, or coaxial cable, when flexed,
generates a charge between the conductors. This
is referred to as triboelectric noise and cannot be
distinguished from the sensor's charge output.
Low-noise cables have a special graphite lubricant
between the dielectric and the braided shield,
which minimizes the triboelectric effect and
improves the quality of the sensor's charge output
signal.

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When using separate cables connect the cable to
the accelerometer. A small amount of thread-
locking compound placed on the connector prior to
attachment helps secure the cable during testing.
In harsh environments, the connection can be
sealed with silicone rubber, O-rings, and flexible
heat-shrink tubing.
2.3 Integral Hardline Cable
For extremely high temperature (>500°F) charge
mode applications use mineral insulated (MI)
hardline. Keep cable clean to maintain insulation
resistance and good low-frequency response
2.4 Hardline Connection Type
2.4.1 PCB / Lemo type connector
The Lemo connector is PCA.0S.302.CLAC42 that
is specially adapted for use with hardline cable.
The connector is a self-latching system that allows
the connector to be mated by simply pushing the
plug axially into the socket. When required the
connector is disengage by a single axial pull on the
outer release sleeve.
2.4.2 High Temperature 2 –pin 7/16-
27 UNS connector
This connector is a Model GP, 2 Pin Jack, 7/16-27
thread. The connector is welded to the hardline to
provide a high temperature, hermetic connection.
The GP connector uses a threaded connction to
mate with a GN or QY 2-Socket plug and torqued
to 5 ft*lbs +/- 1 ft*lb
2.5 Differential Charge Amplifier
The differential charge amplifier is purchased
separately
A conventional method for conditioning the high-
impedance signal generated by a charge output
sensor is to use a differential charge amplifiers
operate from an ICP ® signal conditioner. The unit
employs a high gain amplifier to perform the
impedance transformation. The charge output of
the transducers may be scaled in terms of
acceleration, pressure or force. The output is then
mV/g, mV/psi or mV/lb, respectively.
3 INSTALLATION
OVERVIEW
3.1 Equipment Inspection
Before installing the accelerometer, verify the
insulation resistance (I/R) of the sensor is per
specification. I/R can be out of specification due to
mishandling and/or damage.
3.2 Polarity Test
Use this test to verify the proper polarity response.
Improper polarity will adversely affect the use of the
sensor for machinery diagnostics such as
balancing.
Step 1 –Connect the sensor to a charge amp and
any ICP ® signal conditioner. Using standard
cable, connect the powered sensor to an
oscilloscope.
Step 2 –Set the time scale to 20
milliseconds/division
Step 3 –Hold the transducer in hand and tap the
bottom. The wavefrom on the oscilloscope first
goes positive as shown in Figure 1. If the
waveform goes negative the wiring is reversed,
contact PCB for technical support.
FIGURE 1
3.3 Sensor Location
Characteristics like location, ruggedness,
amplitude range, accessibility, temperature, and
portability are extremely critical.

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For optimum performance and measurement find a
rigid location on the machine casing that most
accurately represents the vibration of the rotor,
bearing, fan, etc. to be measured.).
3.4 Mounting Sensor
When choosing a mounting method, consider closely
both the advantages and disadvantages of each technique.
Characteristics like location, ruggedness, amplitude
range, accessibility, temperature, and portability are
extremely critical. However, the most important and
often overlooked consideration is the effect the mounting
technique has on the high-frequency performance of the
accelerometer.
Shown hereafter are six possible mounting techniques
and their effects on the performance of a typical
piezoelectric accelerometer. (Note that not all of the
mounting methods may apply to your particular sensor.)
The mounting configurations and corresponding graph
demonstrate how the high-frequency response of the
accelerometer may be compromised as mass is added to
the system and/or the mounting stiffness is reduced.
Note: The low-frequency response is unaffected by the
mounting technique. Its roll-off behavior is dependent
upon the coupling type or time constant of the external
charge amplifying device. This characteristic may be
fixed or adjustable, depending on the charge amplifier.
Please refer to the appropriate charge amplifier
specification sheet for information on low-frequency
characteristics.
Figure 1. Assorted Mounting Configurations and Their
Effects on High Frequency
3.4.1 STUD MOUNT
This mounting technique requires smooth, flat contact
surfaces for proper operation and is recommended for
permanent and/or secure installations. Stud mounting is
also recommended when testing at high frequencies.
Note: Do NOT attempt mounting on curved, rough, or
uneven surfaces, as the potential for misalignment and
limited contact surface may significantly reduce the
sensor’s upper operating frequency range.
Figure 2. Mounting Surface Preparation
STEP 1: First, prepare a smooth, flat mounting surface,
then drill and tap a mounting hole in the center of this
area as shown in Figure 2 and in accordance with the
Installation Drawing for the specific sensor that is being
mounted.
A precision-machined mounting surface with a minimum
finish of 63 in (0.00016 mm) is recommended. (If it is
not possible to properly prepare the test structure
mounting surface, consider adhesive mounting as a
possible alternative.) Inspect the area, checking that there
are no burrs or other foreign particles interfering with the
contact surface.
STEP 2: Wipe clean the mounting surface and spread on
a light film of grease, oil, or similar coupling fluid prior
to installation.
Figure 3. Mounting Surface Lubrication
Adding a coupling fluid improves vibration
transmissibility by filling small voids in the mounting
surface and increasing the mounting stiffness. For semi-