The Bently Nevada 330701-00-40-10-02-05 represents the pinnacle of eddy current sensing technology within the 3300 XL 11mm Proximity Transducer System. Engineered for mission-critical industrial assets, this probe provides non-contacting displacement and vibration measurements with surgical precision. While standard 8mm probes suffice for general tasks, this 11mm system excels in applications requiring a wider linear range, such as axial position monitoring, steam turbine differential expansion, and reciprocating compressor rod position.
By utilizing advanced electromagnetic induction, the 330701 sensor captures minute changes in the gap between the probe tip and the target material. It serves as the "eyes" of your Turbine Supervisory Instrumentation (TSI), delivering high-fidelity data to 3500 series racks to prevent catastrophic machinery failure. This probe seamlessly replaces legacy 7200-series 11mm and 14mm systems, offering superior temperature stability and moisture resistance in the harshest power generation and oil & gas environments.
The 330701 series utilizes a specific coding structure to define physical dimensions and certification requirements. Below is the breakdown for the 330701-00-40-10-02-05 configuration:
Unthreaded Length (00): 0 mm. This indicates a fully threaded probe body, allowing for maximum adjustment depth within the mounting bracket.
Overall Case Length (40): 4.0 inches. Provides sufficient reach through machine housings or internal brackets.
Total Length (10): 1.0 Meter (3.3 feet). This defines the length of the integral probe cable before it connects to the extension cable.
Connector Option (02): Miniature coaxial ClickLoc connector. This gold-plated, lockable connector prevents signal loss due to vibration and resists environmental contaminants.
Agency Approval Option (05): Multiple Approvals (CSA, ATEX, IECEx). This ensures the probe meets global safety standards for installation in hazardous (Ex-rated) areas.
| Parameter | Specification Details |
| Probe Tip Diameter | 11 mm (0.43 in) |
| Linear Range | 4.0 mm (160 mils) |
| Scale Factor (Sensitivity) | 3.94 V/mm (100 mV/mil) ±10% |
| Linearity | Less than ±0.15 mm (±5.9 mils) deviation |
| Operating Temperature | -52°C to +177°C (-62°F to +351°F) |
| Thread Type | 1/2-20 UNF |
| System Compatibility | Bently Nevada 3300 XL Proximitor & 3500/42M Monitors |
| Target Material | AISI 4140 Steel (Standard Calibration) |
Success in vibration monitoring depends entirely on the quality of the installation. When installing the 330701 probe, engineers must adhere to the following technical requirements:
Mechanical Gap Setting
The physical gap between the probe tip and the shaft determines the "Bias Voltage" or "Gap Voltage." For a standard 3300 XL 11mm system, the linear range centers at approximately -10 VDC. Use a digital multimeter to measure the voltage at the Proximitor "OUT" and "COM" terminals while adjusting the probe depth.
Cable Protection
Ensure the integral cable maintains a minimum bend radius of 25.4 mm (1.0 in). Avoid over-tightening zip ties, which can crush the coaxial shield and introduce signal noise. Although this specific model (-02-05) does not include stainless steel armor, we recommend routing the cable through external flexible conduit in high-debris areas.
Connector Integrity
The ClickLoc connector system requires a positive "click" to ensure a moisture-proof seal. Do not use pliers to tighten these connectors; finger-tight is sufficient to engage the locking mechanism. Ensure the connectors stay dry and free of oil during the mating process.
The 3300 XL 11mm System provides several distinct advantages over smaller diameter sensors:
Extended Linear Range: It offers a 4.0 mm range, nearly double that of the 8mm probe, which is vital for monitoring thermal growth and differential expansion in large turbines.
Robust Signal Integrity: The 3.94 V/mm sensitivity provides a high signal-to-noise ratio, allowing the sensor to operate reliably even when located long distances from the monitoring rack.
Interchangeability: The 330701 probe is fully compatible with the 3300 XL Proximitor sensor, which automatically compensates for temperature variations, ensuring stable readings from startup to full-load operation.
Hazardous Area Resilience: With the -05 approval rating, this probe operates safely in explosive atmospheres, making it the industry standard for refinery and chemical plant compression strings.
Q1: Can I use the 330701 11mm probe with a standard 8mm 3300 XL Proximitor?
A1: No. The 11mm probe requires a specific 3300 XL 11mm Proximitor. Using an 8mm Proximitor will result in incorrect scale factors and non-linear data, rendering your vibration monitoring system inaccurate.
Q2: How do I verify the probe's health using a multimeter?
A2: You can perform a resistance check. Measure between the center conductor and the outer shield of the ClickLoc connector. A healthy 1.0m probe typically shows a very low resistance (near 0.1 to 1.0 ohms). An "Open" reading indicates a broken internal wire.
Q3: What is the significance of the 1/2-20 UNF thread on this model?
A3: This is the standard English thread size for the 11mm probe body. It ensures compatibility with standard Bently Nevada mounting brackets and bushings used in North American and many international turbine designs.
Q4: Is this probe compatible with the older 7200 series proximity systems?
A4: While the 330701 can physically replace 7200-series 11mm probes, you must upgrade the entire loop (including the extension cable and Proximitor) to the 3300 XL series to ensure performance specifications are met.
