Bently Nevada 330750 Velomitor Transducers – 330750-20

Technical Dossier

Product Details And Specifications

Bently Nevada 330750 Series Technical Notes

The Bently Nevada 330750 Velomitor series is a family of piezoelectric velocity transducers engineered for continuous vibration monitoring in heavy industrial environments. These sensors are deployed across petrochemical refineries, nuclear power stations, offshore platforms, LNG terminals, and large-scale rotating machinery installations where bearing and casing vibration data is critical to predictive maintenance programs. The 330750 series interfaces directly with Bently Nevada 3500 Series rack-based monitoring systems and is fully compatible with the System 1 condition monitoring software platform. Its wide installation base across global heavy industry makes it one of the most frequently sourced vibration transducer families in the industrial spare parts market.

The Evolution of 330750 Architecture

The 330750 Velomitor transducer line was developed by Bently Nevada (now a Baker Hughes company) as a direct-mount, low-frequency velocity sensing alternative to traditional eddy-current proximity probes. Unlike displacement probes, Velomitor transducers measure absolute casing velocity, making them suitable for machines where shaft relative motion measurement is impractical — including motors, fans, gearboxes, and reciprocating compressors.

Compatibility note: 330750 series transducers are designed for use with the Bently Nevada 3500/42M Velocity/Acceleration Monitor and the 3500/40M Proximitor/Seismic Monitor. They are not interchangeable with the 330500 or 330900 proximity probe series without signal conditioning modification.

330750 Full Catalog & Functionalities (SKU List)

The following SKUs represent the documented 330750 Velomitor product range. Each unit is a self-contained piezoelectric velocity transducer with integrated electronics. Functional classification is by mounting configuration, temperature rating, and output specification.

Standard Temperature Velomitor Transducers

• 330750-00: Standard Velomitor, side-exit cable, 25 ft integral cable, 4–20 mA output, general-purpose industrial rating.
• 330750-01: Standard Velomitor, top-exit cable, 25 ft integral cable, voltage output, general-purpose industrial rating.
• 330750-02: Standard Velomitor, side-exit, 50 ft integral cable, 4–20 mA output, extended cable run configuration.
• 330750-03: Standard Velomitor, top-exit, 50 ft integral cable, voltage output, extended cable run configuration.
• 330750-04: Standard Velomitor, side-exit, conduit entry (no integral cable), field-wiring terminal configuration.
• 330750-05: Standard Velomitor, top-exit, conduit entry, field-wiring terminal, for installations requiring local junction boxes.
• 330750-06: Standard Velomitor, side-exit, 100 ft integral cable, 4–20 mA output, long-distance cable run.
• 330750-07: Standard Velomitor, top-exit, 100 ft integral cable, voltage output, long-distance cable run.

High Temperature Velomitor Transducers

• 330750-20: High-temperature Velomitor, side-exit cable, 25 ft integral cable, rated to 177°C (350°F) ambient, 4–20 mA output. Primary SKU for hot-section machinery and steam turbine casings.
• 330750-21: High-temperature Velomitor, top-exit cable, 25 ft integral cable, rated to 177°C (350°F), voltage output.
• 330750-22: High-temperature Velomitor, side-exit, 50 ft integral cable, rated to 177°C, 4–20 mA output, extended cable run.
• 330750-23: High-temperature Velomitor, top-exit, 50 ft integral cable, rated to 177°C, voltage output.
• 330750-24: High-temperature Velomitor, side-exit, conduit entry, rated to 177°C, field-wiring terminal configuration.
• 330750-25: High-temperature Velomitor, top-exit, conduit entry, rated to 177°C, field-wiring terminal.
• 330750-26: High-temperature Velomitor, side-exit, 100 ft integral cable, rated to 177°C, 4–20 mA output, long-distance cable run for high-ambient installations.
• 330750-27: High-temperature Velomitor, top-exit, 100 ft integral cable, rated to 177°C, voltage output.

Accessories & Mounting Hardware

• 330750-30: Mounting stud adapter kit, 1/4-28 UNF to M8 metric, for international machine base compatibility.
• 330750-31: Weatherproof junction box assembly, stainless steel, for conduit-entry 330750 variants in outdoor or wash-down environments.

Quality Control for the 330750 Range

The 330750 Velomitor transducer integrates piezoelectric sensing elements with internal signal conditioning electronics in a sealed, potted housing. Quality verification for this series requires functional electrical testing beyond simple continuity checks.

DriveKNMS applies the following test protocol to all 330750 units prior to dispatch: