Bently Nevada 330500-03-CN Velomitor Piezo-velocity Sensor

Description

Measuring casing vibration velocity directly on rotating machinery, the Bently Nevada 330500-03-CN integrates a rugged piezoelectric accelerometer with an internal integration circuit to output a true velocity signal. This design eliminates the requirement for external signal integration at the monitoring system, providing a robust and less noise-susceptible velocity output directly from the sensor casing. The device is housed in hermetically sealed stainless steel, engineered specifically to withstand severe, high-humidity industrial environments. Standard implementation incorporates a 1/4-28 UNF mounting thread and country-specific agency certifications, ensuring compliance with local plant safety standards.

Features

• Piezoelectric Sensing Element: Incorporates a solid-state internal integrator to output a clean velocity waveform rather than raw acceleration.
• Hermetic Seal: Complete 316L stainless steel enclosure prevents ingress of moisture, oils, and chemical contaminants.
• Two-Pin Mil-C-5015 Connector: Top-exit standard industrial connection interface minimizes installation footprint.
• Electrostatic Shielding: Internal Faraday shield isolates the sensing circuitry from electrostatic interference and electromagnetic fields.

Applications

• Casing vibration measurements on steam and gas turbine bearings.
• Real-time casing velocity monitoring on balance-of-plant machinery including pumps, draft fans, and air compressors.
• Industrial gearbox casing diagnostic monitoring.
• Paper machine dryer roll bearings and harsh wet-end industrial processing zones.

Technical Specifications Table

Connections and Interfaces

Empirical Engineering Insights

Alternative Models & Compatibility

The 330500-03-CN is drop-in backward compatible with older Bently Nevada velocity transducers requiring standard 1/4-28 UNF casing mounting. Always verify monitor channel configuration; when replacing older electro-mechanical velocity sensors (like the 9200 series) with the 330500 piezo-velocity sensor, you must switch the monitor card jumper or software settings from "Seismic" (self-generating) to "Velomitor" (powered -24 VDC constant current) to prevent a transducer OK limit fault.

Application Pitfalls & Engineering Notes

Because the Velomitor utilizes an internal piezoelectric design, rapid ambient temperature variations can induce a transient thermal shock. This thermal expansion or contraction of the crystal mimics low-frequency vibration, triggering spurious "High Velocity" alarms. Avoid mounting the sensor directly opposite uninsulated steam pipe flanges, steam leaks, or cooling vents. If thermal transients are unavoidable, install a heat-insulating boot over the sensor body.

Commissioning & Wiring Tips

Always utilize 2-conductor shielded twisted-pair cabling (such as Bently Nevada 9571) for the signal run. To eliminate ground loops, terminate the cable shield only at the monitoring system / cabinet terminal strip. Cut the shield flush and insulate it with heat-shrink at the sensor's MIL connector end. Ensure the sensor mounting surface is machined flat to a surface finish of 0.8 micrometers (32 microinches) Ra to guarantee precise high-frequency mechanical transmission.

Installation Guidelines