The Bently Nevada 330105 is a reverse mount probe from the 3300 XL series 8 mm eddy current transducer system. This system is an industry standard for condition monitoring of rotating machinery, widely used for vibration, displacement, speed, and Keyphasor measurements on turbines, compressors, fans, pumps, and other critical equipment.
The 3300 XL 8 mm system is known for its advanced performance, high reliability, and complete interchangeability. The 330105 probe features a 3/8-24 UNF thread and is specifically designed for applications requiring reverse mounting (i.e., installing from inside the machine outward). This design simplifies installation in tight spaces or special machine configurations.
The system fully complies with the American Petroleum Institute (API) 670 Standard for mechanical configuration, linear range, accuracy, and temperature stability. All 3300 XL 8 mm components (probes, extension cables, and Proximitor sensors) are fully interchangeable, eliminating the need for matching or bench calibration of individual components.
2. System Components
A complete 3300 XL 8 mm eddy current transducer system consists of three core components:
330105 3300 XL 8 mm Reverse Mount Probe – Directly senses the distance to the conductive surface (e.g., shaft). The reverse mount design distinguishes it from standard forward mount probes.
3300 XL Extension Cable – Connects the probe to the Proximitor sensor. The total system length (probe cable length + extension cable length) must match the Proximitor sensor’s rated length (e.g., 5 m or 9 m). The 330105 probe is typically used with standard or armored extension cables (e.g., 330130 series).
3300 XL Proximitor Sensor – Supplies a high-frequency carrier signal to the probe, demodulates and amplifies the gap voltage. The output is a negative DC voltage proportional to the gap (typically -0 Vdc to -18 Vdc or -24 Vdc linear range). Common model: 330180 series.
Important Notes:
1-meter systems do not use an extension cable; the probe connects directly to the Proximitor.
Factory default calibration target material is AISI 4140 steel. Calibration to other target materials is available upon request.
3. Key Features and Advantages
The 330105 probe incorporates many advanced designs from the 3300 XL series, ensuring long-term stability in harsh industrial environments.
3.1 Robust Mechanical Design
TipLoc™ Molding – Patented probe tip molding provides a robust bond between the probe tip and body, preventing loosening or rotation, significantly improving vibration and shock resistance.
CableLoc™ Design – The cable-to-probe body connection uses the patented CableLoc design, with pull strength up to 330 N (75 lbf), ensuring the cable does not detach under high stress.
Reverse Mount Configuration – The probe body has threads near the tip. It is installed from inside the machine outward and secured with a lock nut. This avoids handling long cables outside the machine and simplifies installation in confined spaces.
3.2 Reliable Electrical Connection
ClickLoc™ Gold-Plated Connectors – Corrosion-resistant ClickLoc connectors between probe and extension cable require only finger tightening (an audible “click” indicates full engagement). The special locking mechanism prevents loosening due to vibration. No special tools are needed.
Connector Protectors – Optional connector protectors provide additional environmental protection against oil, moisture, and dust. The datasheet recommends connector protectors for all installations.
3.3 High RFI/EMI Immunity
The 3300 XL Proximitor sensor and probe system exhibit high immunity to radio frequency and electromagnetic interference. Even when installed in fiberglass housings, nearby radio signals cause no adverse effects. The improved immunity meets European CE mark requirements without special shielded conduit or metal housings, reducing installation cost and complexity.
3.4 Easy Installation and Maintenance
SpringLoc Terminal Strips – The Proximitor sensor’s SpringLoc terminal strips require no special tools. They provide fast, robust, vibration-resistant wiring connections, eliminating screw-type clamps that can loosen.
Complete Interchangeability – 3300 XL 8 mm components (including the 330105 probe) are both electrically and physically interchangeable with non-XL 3300 series 5 mm and 8 mm components. However, mixing XL and non-XL components limits system performance to the non-XL specifications.
4. Installation Considerations
Thread Engagement Length – For 3/8-24 UNF threads, the maximum recommended engagement length is 0.563 inch (approx. 14.3 mm). Exceeding this may cause binding during installation. Bently Nevada does not replace probes damaged by excessive thread engagement.
Lock Nut – Optional probe lock nut with safety wire holes (part number 04301007) is available for 3/8-24 threads to secure the probe.
Connector Protectors – Strongly recommended for all installations. Silicone tape (supplied with extension cables) is not recommended for connections exposed to turbine oil.
FluidLoc Option – The datasheet notes that for the 330105 reverse mount probe, the presence of the probe sleeve makes the FluidLoc cable option unnecessary for the vast majority of installations. Order option -12 only if leakage through the cable interior is a genuine concern.
