Part number 139976-01
Revision B, February 1999
330450
HIGH
TEMPERATURE
ACCELEROMETER
SYSTEM
OPERATION MANUAL
330450 High Temperature Accelerometer System
Copyright © 1998 Bently Nevada Corporation
All Rights Reserved.
The information contained in this document is subject to change without notice.
The following are trademarks of Bently Nevada Corporation in the United States
and other countries:
Actionable Information™ , Actionable Information to
the Right People at The Right Time™ , ADRE®, Bently
Nevada®, CableLoc™ , Data Manager®, Decision
Support™ , DemoNet™ , Dynamic Data Manager®,
Dynamic Transmitor™ , Engineer Assist™ ,
FieldMonitor™ , FluidLoc™ , flexiTIM™ , flexiTAM™ ,
Helping You Protect and Manage All Your
Machinery®, HydroVU™ , Key ∅ ®, Keyphasor®,
Machine Condition Manager™ 2000,
MachineLibrary™ , MicroPROX®, Move Data, Not
People™ , Move Information, Not Data™ , Performance
Manager™ , PROXPAC®, Proximitor®, REBAM®,
Seismoprobe®, System 1™ , TDIXconnX™ ,
Tecknowledgy™ , TipLoc™ , TorXimitor®, Transient
Data Manager®, Trendmaster®, TrimLoc™ , VAM™ ,
Velomitor®, Xlerometer™
The Bently Nevada Corporation Orbit Design is a
trademark of Bently Nevada Corporation in the United
States and other countries.
The following ways of contacting Bently Nevada Corporation are provided for
those times when you cannot contact your local Bently Nevada representative:
Mailing Address 1617 Water Street
Minden, NV 89423
USA
Telephone 1 702 782 3611
1 800 227 5514
Fax 1 702 782 9259
Internet www.bently.com
Customer and third parties that are in control of product at the end of its life or
at the end of its use are solely responsible for proper disposal of product. No
person, firm, corporation, association or agency that is in control of product shall
dispose of it in a manner that is in violation of United States state laws, United
States federal laws, or any applicable international law. Bently Nevada
Corporation is not responsible for disposal of product at the end of its life or at
the end of its use.
ii
Contents
Note:
This manual shows how to install, wire and verify the operation of the
330450 High Temperature Accelerometer System. Document 159859-
01 is attached to the end of this manual for further reference. It contains
specifications and ordering information for the sensor and is referenced
throughout the manual as the “Specifications and Ordering Information”
datasheet.
Section 1 — Operating Information....................................................1-1
Application .................................................................................................................... 1-1
Principle of Operation.................................................................................................... 1-2
Section 2 — Installation.......................................................................2-1
Receiving Inspection ..................................................................................................... 2-1
Installing the 330450 ..................................................................................................... 2-1
Positioning the Sensor............................................................................................... 2-1
Mounting.................................................................................................................... 2-1
Grounding ..................................................................................................................... 2-4
Installing Interconnect Cable ......................................................................................... 2-4
Routing Cable............................................................................................................ 2-4
Routing Conduit......................................................................................................... 2-4
Routing Armored Cable ............................................................................................. 2-4
Sealing the Interconnect Cable.................................................................................. 2-5
Power and Signal Connections ..................................................................................... 2-5
External Power Supply .............................................................................................. 2-6
Section 3 — Maintenance....................................................................3-1
Performance Test Procedure ........................................................................................ 3-1
Polarity Test Procedure................................................................................................. 3-2
Section 4 — Field Testing and Troubleshooting...............................4-1
Bently Nevada Monitor OK LED is off ........................................................................... 4-1
Non-Machine related signal........................................................................................... 4-2
Section 5 — Cables and Installation Accessories ............................5-1
Mounting Accessories ................................................................................................... 5-4
iii
330450 High Temperature Accelerometer System
iv
Operating Information
Section 1 — Operating Information
Application
Accelerometers measure machinery casing vibration. They are typically used on
machines where the use of eddy current proximity transducers is not practical.
Application Advisory
If a machine is to be protected by measuring the casing vibration,
evaluate the usefulness of the measurement for each application.
Most common machine malfunctions, such as imbalance or
misalignment, occur on the rotor and are revealed as an increase (or
at least a change) in rotor vibration. In order for a casing
measurement alone to effectively protect a machine, a significant
amount of rotor vibration must be faithfully transmitted to the
machine casing or mounting location of the sensor. Carefully
choose a mounting position that is most sensitive to this vibration.
Improper installation may decrease the amplitude and frequency
response of the sensor or generate false signals that do not
represent vibration originating from the rotating element(s).
Application Advisory
This manual is not intended to describe the proper ways to interpret
the data produced by the sensor or any system in which the sensor
is employed. In addition, the fact that the sensor is installed in
conformance with the instructions of this manual should not be
misconstrued that the sensor is necessarily useful in its particular
application. Considerable training and understanding is required to
properly assess the quality of the sensor’s measurement. For more
information about proper measurement technique, contact a
qualified Bently Nevada Machinery Management Services (MMS)
representative.
1-1
330450 High Temperature Accelerometer System
Principle of Operation
Figure 1-1: 330450 Accelerometer
The 330450 consists of three main components: a transducer, an integral cable, and
an electronics assembly (see Figure 1-1). The transducer consists of a piezoelectric
ceramic stack that is pre-stressed between the base of the transducer and a
reference mass. When subjected to machinery vibration, this mass/spring system
exerts a force on the piezoelectric ceramic that generates a charge signal
proportional to the driving force. This signal is then sent to the electronics assembly
via the integral cable that is permanently installed between the transducer and
electronics. When the signal reaches the electronics, it is converted to a voltage
signal, amplified and filtered to produce a low-noise output signal proportional to
acceleration. Separation of the electronics and transducer allows placement of the
transducer in high temperature environments that cannot be tolerated by the
electronics.
Application Advisory
A piezoelectric accelerometer subjected to a sudden mechanical
impulse or a large, fast temperature gradient may generate low
frequency signals that do not represent actual machinery vibration.
This signal could trip alert or danger relays. Double integration of
the output signal to displacement further magnifies these low
frequency signals. For this reason, it is not recommend that the
output of the 330450 be double integrated to displacement.
The 330450 is designed to monitor vibration frequencies ranging from 15 Hz to 10
kHz (900 cpm to 600,000 cpm). The scale factor is 10.2 mV/(m/s2 ) (100 mV/g) and
can measure a peak acceleration level up to 784 m/s2 (80 g). Reference the
“Specifications and Ordering Information”datasheet for more details on the sensor’s
operating range.
1-2
Operating Information
Figure 1-2: 330450 Block Diagram
The 330450 is a three-wire sensor which requires an external power supply (see Figure 1-2).
The sensor’s internal circuitry automatically sets the DC output bias when supplied with a
voltage in the range of -15 to -30 Vdc. However, the sensor will accurately measure the
specified peak acceleration range only when supplied with a voltage of -24 to -30 Vdc.
It is recommended that the sensor always be supplied with a voltage of -24 to -30 Vdc.
The DC bias and AC signal appears between pins "A" and "C". Compatible Bently Nevada
monitoring systems can power the 330450 without additional external circuitry.
1-3
330450 High Temperature Accelerometer System
1-4
Installation
Section 2 — Installation
This section describes how to mount the transducer and electronics and presents
guidelines for connecting and routing the integral cable and the interconnect cable.
Receiving Inspection
Inspect the components of the order upon receipt for any damage that may have
occurred during shipping. Keep all shipping forms and invoices. If any shipping
damage is apparent, file a claim with the carrier and submit a copy to Bently Nevada
Corporation. Include all model numbers and serial numbers with the claim. We will
either repair or replace damaged parts according to the terms and conditions of the
sale.
The 330450 is shipped in a foam-filled package and the connector is protected with a
screw-on plastic cap. The 330450 is a sensitive instrument and these precautions help
to prevent damage during shipping.
Hardware such as transducer mounting bolts, weatherproof housings and interconnect
cable must be purchased separately. Reference Section 5 and the “Specifications and
Ordering Information”datasheet for accessories and ordering information.
Installing the 330450
Positioning the Sensor
For optimum performance and accurate measurements, place the 330450 at a location
on the machine casing that will allow it to most accurately measure the vibration
originating at the rotor. Proper placement often depends on the application. Bently
Nevada offers Machinery Management Services, whose engineers can help determine
the optimum sensor location for your application.
Mounting
To install the 330450 accelerometer:
Table 2-1: Operating Temperature Range
System Component Operating Temperature Range
°C °F
Transducer -55 to 400 -67 to 752
Integral Cable -55 to 400 -67 to 752
Electronics Assembly -55 to 125 -67 to 257
2-1
330450 High Temperature Accelerometer System
Step 1- Verify that the
ambient and surface
temperatures of the
installation location are within
the temperature rating of the
sensor as shown in Table
2-1.
Step 2- Verify that the
mounting site is flat, clean
and dry. The transducer
requires a flat area that is
38.1 X 38.1 mm (1.5 X 1.5 in)
for mounting. For best
results, the mounting surface
should have a roughness of
no more than 0.813 µm (32
µin) RMS and a flatness of at
least 25.4 µm (0.001 in) TIR
(see Figure 2-1).
Figure 2-1: Mounting Surface Preparation
Step 3- Drill and tap holes in
the mounting surface as
required by the mounting
bolts. Figure 2-1 gives the
locations for the mounting bolt
holes as required by the
transducer. The sensitive axis
of the transducer (see Figure
2-2) must be parallel to the
axis of the desired
measurement.
Step 4- Place the transducer
on the mounting surface and
torque each mounting bolt
equally to avoid deforming the
transducer base. The
maximum diameter of the bolt
head that can be used with the
transducer is 6.35 mm (0.250
in). The mounting holes will
accept either an M3 or #6 screw.
Figure 2-2: Mounting the Transducer
2-2
Installation
0.15 m
(6 in)
Figure 2-3: Integral Cable Tie Down
Step 5- Route the integral cable away from any points that may exceed its operating
temperature. Avoid twisting, kinking or straining the integral cable. Avoid any points
where abrasion could damage the integral cable. The minimum bend radius of the
integral cable is 6.35 mm (0.25 in). Secure the integral cable at 0.5 m (1.5 ft) intervals
to prevent excessive movement. The tie down closest to the transducer end of the
sensor should not be more than 0.15 m (6 in) away from the transducer and should be
attached to the same surface that the transducer is mounted (see Figure 2-3).
Step 6- Mount the electronics housing at a location within the specified temperature
range (see Table 2-1). Choose a location that facilitates the mounting of the
electronics package and provides mechanical isolation from vibration (see Figure 2-4).
Avoid exceeding the minimum bend radius of the integral cable when mounting the
electronics package.
Figure 2-4. Electronics Assembly Installation
2-3
330450 High Temperature Accelerometer System
Grounding
It is imperative that the case of the accelerometer (that is the transducer, electronics
assembly or hardline) be grounded; otherwise, the unit will be very susceptible to
extraneous electrical noise. The potential between machine ground and signal ground
should be less than 0.5 V. In addition, the resistance between earth ground and the
accelerometer case should be less than 1 Ω.
Installing Interconnect Cable
The interconnect cable must be purchased separately. Section 5 and the
“Specifications and Ordering Information”datasheet describe the interconnect cables
and explains how to order them.
Routing Cable
When installing the interconnect cable, route it away from the moving components of
the machine and avoid sharp corners. To minimize noise, avoid routing cables near or
in the same conduit, raceway, or cable tray with power lines. Prevent the cable from
bending sharply, twisting, kinking, knotting, or being unduly strained. To prevent
physical damage, route the cable through conduit. If the cable must be routed inside
lubrication oil lines, be sure it will not be subjected to temperatures exceeding its
specified operating range (reference “Specifications and Ordering Information”
datasheet).
Routing Conduit
To route cable through conduit, connect one end of the conduit to the protective
enclosure or other structure in which the monitor is mounted. Connect the other end of
the conduit rigidly to a structure near the 330450. Before pulling cable through conduit,
protect the connector by wrapping it with tape or a similar covering. Be sure that the
cable does not rub against rough or sharp surfaces.
Routing Armored Cable
If the cable is not routed inside conduit, use armored cable and secure it to supporting
surfaces with clips or similar devices. Route the cable through protected areas to
reduce the chance of damage. Connect one end of the armor directly to the enclosure
or other structure in which the monitor is mounted. Connect the other end of the armor
rigidly to a structure near the electronics. The recommended minimum bend radius for
armored cable is 38.1 mm (1.5 in).
2-4
Installation
Sealing the Interconnect Cable
Application Alert
When conduit is routed through hazardous areas,
the ends of the conduit must be sealed to prevent
hazardous gases from escaping into non-
hazardous areas. Consult local authorities for
approved sealing methods in hazardous areas.
Table 2-2 describes the strategies that should be used to seal conduit in non-hazardous areas
and the differential pressures at which they apply. Bently Nevada cable seals protect against
splash and abrasion but they do not protect against immersion. Contact Bently Nevada if
greater protection is required.
Table 2-2 . Conduit Sealing Techniques for Non-Hazardous Areas
Differential Pressure Seal Type
Less than one atmosphere ZY5 cable seal similar to Bently
Nevada P/N 10076-01 for unarmored
cable
Greater than one atmosphere Special interconnecting cable
(Contact Bently Nevada for details)
Power and Signal Connections
Bently Nevada Corporation supplies interconnect cables with terminal lugs and a 3-
socket mating connector for the 330450 accelerometer. Interconnect cables are sold
separately (reference “Specifications and Ordering Information”datasheet).
At the accelerometer end, tighten the 3-socket mating connector to the accelerometer
MIL-C-5015 connector.
Note: The wiring instructions assume that the interconnect cable is the standard Bently
Nevada cable part number 16925.
2-5
330450 High Temperature Accelerometer System
External Power Supply
Before connecting the accelerometer, turn on the power supply and adjust the voltage
to -24 Vdc to -30 Vdc. Set the current limit of the power supply (see Application Alert)
to be less than or equal to 15 mA. Turn the supply off. Using the 16925 interconnect
cable, connect the “B”lead to the “-“terminal of the power supply and the “C”lead to
the “+”terminal of the power supply. The “A”lead of the cable is the output of the
accelerometer. Turn the power supply on, verify the voltage and current limit settings
and measure the dc voltage of lead “A”with respect to lead “C”. The voltage should be
-12.00 ± 0.25 Vdc. If it is not, turn off the power supply immediately and check to see
that the transducer is connected properly. The terminal connection diagram of the
external power supply appears in Figure 2-5.
Application Alert
When connecting the accelerometer to an external
power supply, the current supply to the
accelerometer should be limited to 15 mA. If the
accelerometer is improperly connected and the
current supply is not limited sufficiently, then the
unit could be permanently damaged.
2-6
Installation
Figure 2-5: External Power Supply Connection Diagram
2-7
330450 High Temperature Accelerometer System
2-8
Maintenance
Section 3 — Maintenance
This section describes how to check the performance of the 330450. If the
equipment listed in the procedure below is not available, contact the nearest
Bently Nevada Corporation field office or return the transducer to the factory for
testing.
Performance Test Procedure
Step 1- Mount the accelerometer on a calibrated shake table.
Step 2- Connect the accelerometer to a power supply as described on pg. 2-
6. Make sure that the case of the 330450 is grounded to signal common
Step 3- Connect the voltmeter between pin A and pin C.
Step 4- Shake the accelerometer at 100 Hz with a known acceleration level.
Step 5- Verify the accelerometer provides an output voltage corresponding to
a scale factor of 100 mV/g ±5%.
3-1
330450 High Temperature Accelerometer System
Polarity Test Procedure
Use this test to verify the proper phase response. Improper phase will
adversely affect the use of the 330450 for machinery diagnostics.
Step 1- Connect the 330450 as shown in Figure 2-5.
Step 2- Set the time base on the oscilloscope to 20 milliseconds/division.
Step 3- Hold the transducer in hand and tap the bottom. Observe that the
waveform on the oscilloscope first goes positive as shown in Figure 3-1. If the
waveform goes negative first, contact the nearest Bently Nevada office for
assistance.
Display Goes
Positive First
Time
Figure 3-1. Polarity Check Oscilloscope Display
3-2
Field Testing and Troubleshooting
Section 4 — Field Testing and
Troubleshooting
Use the following procedures to test an installed 330450 and isolate a suspected
malfunction. The 330450 is a hermetically sealed unit with no adjustments or field
repairable components. If you determine that the 330450 is not functioning properly,
contact the nearest Bently Nevada office for assistance.
When the 330450 is used with a Bently Nevada monitoring system, a sensor fault is
indicated when the monitor's OK LED goes OFF. A fault may be due to a sensor
malfunction or a malfunction in the field wiring. Before troubleshooting a suspected
problem, check that the sensor has been correctly installed and that all connections are
secured and in the proper locations. If the sensor is properly installed, use the
following steps to help identify the problem.
Bently Nevada Monitor OK LED is off
Monitor Power is off.
Check that the monitor power supply is plugged in and power is on.
Interconnect cable is disconnected, connected loosely, or connected to the wrong
monitor.
Verify that the sensor is connected to the correct monitor and to the correct monitor
terminals. Check that the terminal screws are tight.
Sensor is open or shorted
Disconnect the interconnect cable from the monitor or power supply. Measure the
resistance across sensor terminals "A-C" and “B-C.” The resistance should be between
4 MΩ to 6 MΩ and 800 kΩ to 1.2 MΩ, respectively. The polarity of the of the ohm-
meter should not have a significant effect on the resistance reading.
Interconnect cable is damaged: Shorted
Visually inspect the interconnect cable for apparent damage. Disconnect the
interconnect cable at both ends and measure the resistance between each of the three
conductors and between each conductor and the shield of the interconnect cable. If
the measurement indicates an intermittent or shorted cable, replace the cable.
Interconnect cable is damaged: Open
Disconnect the interconnect cable at both ends. Short two of the three conductors of
the cable at one end and measure their resistance at the other end. If the cable is
open circuited, replace the cable. Then short the remaining, untested conductor with
one of the other, tested conductors and measure their resistance at the other end. If
the cable is open circuited, replace the cable.
Cable conductors are switched
With the sensor and interconnect cable connected, measure the DC voltage of terminal
"A" referenced to terminal "C" at the monitor. The voltage should be -12.00 ± 0.25 Vdc.
If it is not, check to see that the sensor is properly connected.
4-1
330450 High Temperature Accelerometer System
Non-Machine related signal
Sensor signal is not isolated, is shorted to the case, or has noise coupled
to the signal.
Remove the interconnect cable from the sensor and measure the resistance
between each sensor pin and the case of the 330450. If the resistance is not
40 MΩ or greater, replace the sensor.
Loose or dirty connection at the sensor
Remove the interconnect cable from the sensor. Clean the connector and
check for frayed or broken insulation on the interconnect cable. Clean the
connector on the sensor. Reattach the interconnect cable to the sensor making
sure that the connection is tight and dry.
Loose connection at the monitor
Check the connections at the back of the monitor. Retighten if necessary.
Sensor’s case is improperly grounded
It is imperative that the case of the accelerometer is grounded; otherwise, the
unit will be very susceptible to extraneous electrical noise. Ideally, the machine
ground and signal common should be at the same voltage potential. To check
for this, remove the interconnect cable from the sensor. The interconnect cable
still needs to be connected to the monitor (or power supply). Then, with an AC
voltmeter, measure the voltage between socket “C”of the interconnect cable’s
connector and the sensor case. This voltage should be less than 0.5 V. In
addition, using an ohmmeter, check that the resistance between earth ground
and the accelerometer case is less than 1 ohm. A higher voltage or resistance
is a possible indication of a grounding problem external to the monitor and
sensor. This problem must be corrected in order for the sensor to operate
properly.
4-2
Cables and Installation Accessories
Section 5 — Cables and Installation
Accessories
Reference “Specifications and Ordering Information”datasheet for interconnect cable
details.
Figure 5-1: Standard Interconnect Cable
5-1
330450 High Temperature Accelerometer System
Figure 5-2: Standard Armored Interconnect Cable
5-2
Cables and Installation Accessories
Figure 5-3: Splash Resistant Interconnect Cable
5-3
330450 High Temperature Accelerometer System
Mounting Accessories
1-inch rigid conduit strap for securing the
electronics housing. Part number 03818073
1-inch weather tight hub used to mount the
electronics housing in a weatherproof enclosure.
Part number 03818071
1 inch sealing lock ring. Use sealing lock ring to
mount the electronics housing. Two rings are
required to mount the electronics. Part number
03818072
Stainless steel tie down used to secure the 0.125”
diameter integral cable. The quantity used varies
based upon the length option purchased. See
Figure 2-3 for spacing requirements of tie downs.
Part number 03810111
Figure 5-4: Mounting Accessories
5-4
Part Number 139976-01
