330505 Low Frequency Velocity Sensor0 pages
330505 Low Frequency Velocity Sensor
nnnnBently Nevada* Asset Condition Monitoring
nnnnBENTLY
nnnnNEVADA
nnnnLOW FREQUENCY VELOCITY SENSOR
nnnn20 mV/mm/s (508 mV/in/s)
nnnnORIENTATION: VERTICAL 0-
nnnnS/N: XXXXXX
nnnnP/N: 330505-01
nnnnC€
nnnnDescription
nnnnThe Bently Nevada Low Frequency Velocity Sensor is designed to measure
nnnnabsolute (relative to free space) bearing housing, casing, or structural
nnnnvibration. The two-wire system consists of a transducer and appropriate
nnnncable.
nnnnThe Low Frequency Velocity Sensor is ideal for capturing vibration data in
nnnninstallations where vibration frequencies of less than 4 Hz provide valuable
nnnndata. Its main use is to measure bearing casing vibrations on hydroelectric
nnnnturbines where slow rotating speeds require a low signal to noise ratio. The
nnnn330505 Transducer is a two-wire design that uses moving-coil technology
nnnnwith embedded signal conditioning circuitry to provide a voltage output
nnnndirectly proportional to the transducer's vibration velocity. The 330505
nnnnTransducer connects to an interconnect cable and is then directly attached
nnnninto the 3500/46M Hydro Monitor. This transducer currently does NOT
nnnninterface with the Trendmaster* family of products. Additionally, due to
nnnncapacitance constraints, hazardous area approvals will NOT be available on
nnnnthis product.
nnnnA Caution
nnnnDue to the nature of high amplitude, low frequency velocity events, the
nnnn330505 Low Frequency Velocity Sensor cannot be used for automated
nnnnmachinery protection. It is designed to provide early warning of pending
nnnnmachinery problems and to assist in diagnosing machinery problems. False
nnnnalarms or trips could potentially result if the velocity signal is integrated to
nnnndisplacement in the 3500/46M and used as an alarm or shutdown protection
nnnnparameter. Small electrical disturbances or mechanical "spikes" can cause a
nnnnlarge output from the displacement integrator that may take several minutes
nnnnto settle below the alarm or trip level. This is especially true when integration
nnnnis performed at a low frequency (below 1Hz). The 3500/46M monitor has the
nnnncapability to set long alarm or trip time delays to avoid these false alarms as
nnnnlong as the time delays are compatible with machine's protection
nnnnrequirements. If the velocity output is used rather than displacement as the
nnnnprotection parameter, the sensor is suitable for use as an input to a
nnnnprotection system.
nnnnIn addition, care should be exercised in the physical installation of the
nnnntransducer. Improper installation can result in a degradation of the
nnnntransducer's performance, and/or the generation of signals which do not
nnnnrepresent actual machine vibration.
nnnnUpon request, we can provide engineering services to determine the
nnnnappropriateness of housing measurements for the machine in question
nnnnand/or to provide installation assistance.
nnnnNote: For the majority of installations, our Velomitor* family of velocity transducers, which
nnnnincorporate solid-state technology, represent superior performance and robustness for casing
nnnnimagination at work
nnnnSpecifications and Ordering Information
nnnnPart Number 169872-01
nnnnRev. B (01/10)
nnnnPage lof 11
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