330505 Low Frequency Velocity Sensor0 pages

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330505 Low Frequency Velocity Sensor

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Bently Nevada* Asset Condition Monitoring

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BENTLY

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NEVADA

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LOW FREQUENCY VELOCITY SENSOR

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20 mV/mm/s (508 mV/in/s)

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ORIENTATION: VERTICAL 0-

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S/N: XXXXXX

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P/N: 330505-01

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C€

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Description

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The Bently Nevada Low Frequency Velocity Sensor is designed to measure

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absolute (relative to free space) bearing housing, casing, or structural

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vibration. The two-wire system consists of a transducer and appropriate

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cable.

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The Low Frequency Velocity Sensor is ideal for capturing vibration data in

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installations where vibration frequencies of less than 4 Hz provide valuable

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data. Its main use is to measure bearing casing vibrations on hydroelectric

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turbines where slow rotating speeds require a low signal to noise ratio. The

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330505 Transducer is a two-wire design that uses moving-coil technology

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with embedded signal conditioning circuitry to provide a voltage output

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directly proportional to the transducer's vibration velocity. The 330505

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Transducer connects to an interconnect cable and is then directly attached

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into the 3500/46M Hydro Monitor. This transducer currently does NOT

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interface with the Trendmaster* family of products. Additionally, due to

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capacitance constraints, hazardous area approvals will NOT be available on

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this product.

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A Caution

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Due to the nature of high amplitude, low frequency velocity events, the

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330505 Low Frequency Velocity Sensor cannot be used for automated

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machinery protection. It is designed to provide early warning of pending

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machinery problems and to assist in diagnosing machinery problems. False

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alarms or trips could potentially result if the velocity signal is integrated to

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displacement in the 3500/46M and used as an alarm or shutdown protection

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parameter. Small electrical disturbances or mechanical "spikes" can cause a

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large output from the displacement integrator that may take several minutes

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to settle below the alarm or trip level. This is especially true when integration

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is performed at a low frequency (below 1Hz). The 3500/46M monitor has the

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capability to set long alarm or trip time delays to avoid these false alarms as

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long as the time delays are compatible with machine's protection

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requirements. If the velocity output is used rather than displacement as the

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protection parameter, the sensor is suitable for use as an input to a

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protection system.

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In addition, care should be exercised in the physical installation of the

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transducer. Improper installation can result in a degradation of the

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transducer's performance, and/or the generation of signals which do not

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represent actual machine vibration.

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Upon request, we can provide engineering services to determine the

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appropriateness of housing measurements for the machine in question

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and/or to provide installation assistance.

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Note: For the majority of installations, our Velomitor* family of velocity transducers, which

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incorporate solid-state technology, represent superior performance and robustness for casing

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imagination at work

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Specifications and Ordering Information

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Part Number 169872-01

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Rev. B (01/10)

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