Description
These accelerometers are intended for critical machinery
applications where casing acceleration measurements are
required, such as gear mesh monitoring. The 330400 is
designed to address the requirements of American Petroleum
Institute Standard 670 for accelerometers. It provides an
amplitude range of 50 g peak and a sensitivity of 100 mV/g.
The 330425 is identical except it provides a larger amplitude
range (75 g peak) and a sensitivity of 25 mV/g.
If housing measurements are being made for overall
protection of the machine, thought should be given to the
usefulness of the measurement for each application. Most
common machine malfunctions (imbalance, misalignment,
etc.) originate at the rotor and cause an increase (or at least a
change) in rotor vibration. In order for any housing
measurement alone to be effective for overall machine
protection, a significant amount of rotor vibration must be
faithfully transmitted to the bearing housing or machine
casing, or more specifically, to the mounting location of the
transducer.
In addition, care should be exercised in the physical
installation of the transducer. Improper installation can result
in a degradation of the transducer’s performance, and/ or the
generation of signals which do not represent actual machine
vibration. Integration of the output to velocity can worsen
this. Extreme caution should be exercised if integrating to
velocity. For high quality velocity measurements the 330500
Velomitor Sensor should be used.
Upon request, we can provide engineering services to
determine the appropriateness of housing measurements for
the machine in question and/or to provide installation
assistance
Specifications
Parameters are specified from +20 to +30 °C
(+68 to +86 °F) and 100 Hz unless otherwise
indicated.
Operation outside the specified limits may
result in false readings or loss of machine
monitoring.
Electrical
330400
Sensitivity 10.2 mV/m/s2 (100 mV/g) ±5%.
Acceleration
range
490 m/s2 (50 g) peak overall
acceleration within the 10 Hz to 15
kHz frequency span. Vibration at
frequencies above 15 kHz, especially
at the transducers resonance will
significantly decrease this range.
Amplitude
Linearity
±1% to 490 m/ s2 (50 g) peak.
Broadband
Noise Floor
(10 Hz to 15
kHz)
0.039 m/s2 (0.004 g) rms.
330425
Sensitivity 2.5 mV/m/s2 (25 mV/g) ±5%.
Acceleration
Range
735 m/s2 (75 g) peak overall
acceleration within the 10 Hz to 15
kHz frequency span. Vibration at
frequencies above 15 kHz, especially
at the transducer’s resonance, will
significantly decrease this range.
Amplitude
Linearity
±1% to 735 m/s2 (75 g) peak.
Broadband
Noise Floor
(10 Hz to 15
kHz)
0.098 m/s2 (0.01 g) rms.
Both Units
Frequency
Response
10 Hz to 15 kHz
(600 cpm to 900,000 cpm) ±3dB;
30 Hz to 10 kHz
(1800 cpm to 600,000 cpm) ±10%
Temperature
Sensitivity
-11% to +3% typical over the
operating temperature range.
Transverse
Sensitivity
Less than 5% of axial.
Mounted
Resonant
Frequency
Greater than 30 kHz.
Amplitude of
Resonant
Peak
20 dB maximum.
Base Strain Sensitivity
For serial
numbers
preceded by
the letter “G”
(including all
new sensors
49 mm/s2/mstrain (0.005 g/mstrain)
For serial
numbers NOT
preceded by
the letter “G”
(shipped
prior to April
2004)
980 mm/s2/mstrain (0.100 g/mstrain)
without Mounting Base (API
adapter);
4.9 mm/s2/mstrain (0.0005 g/mstrain)
with Mounting Base (API adapter)
supplied with the accelerometer.
Bently Nevada recommends
installing with the Mounting base to
minimize base strain sensitivity for
serial numbers NOT preceded by the
letter “G”.
Maximum
cable length
305 metres (1000 ft) with no
degradation of signal.
Power requirements
Input Voltage -24 ± 0.5 Vdc.
Bias Current 2 mA nominal.
Output Bias
Voltage:
-8.5 ± 0.5 Vdc.
Grounding Case isolated.
Environmental Limits
330400 and 330425 Accelerometer Acceleration Transducers
Datasheet
2/10 141638 Rev. W
Operating
and storage
temperature
-55°C to +121°C (-67°F to +250°F)
Shock
Survivability
49,050 m/s2 (5000 g) peak, maximum.
Relative
humidity
100% condensing, non-submerged.
Case is hermetically sealed.
Magnetic
Field
Susceptibility
<2.21 mm/s2/gauss (225 mg/gauss)
[50 gauss, 50-60Hz].
IP Rating Equivalent to an IP 68 (Dust tight and
watertight). Please note that this is
for the sensor only and does not
apply to the cable.
Physical
Weight (no
cable)
99 g (3.5 oz), typical
Diameter 23 mm (0.93 in).
Height 59 mm (2.3 in), including mounting
stud.
Connector 3-pin MIL-C-5015 Receptacle
316L stainless steel
Mounting
Surface
32 minch rms.
Mounting
Torque
4.1 N·m (3.0 ft·lb).
Case Material 316L stainless steel
Weight (no
cable)
100 g (3.5 oz), typical
Mounting
Angle
Any orientation
330400 and 330425 Accelerometer Acceleration Transducers
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