Product Overview

The 330851-02-000-060-10-00-CN (330851-02-000-060-10) is a heavy-duty 25 mm eddy-current proximity probe from Bently Nevada's renowned 3300 XL series. Engineered for large-scale rotating machinery, this probe is designed to measure vibration, differential expansion, and thrust position in environments where standard 8 mm probes lack the necessary linear range. The 25 mm tip provides an extended measurement envelope, making it the primary choice for monitoring large steam turbines and compressors in power generation and heavy industrial sectors. By delivering precise, non-contact displacement data, the 330851-02-000-060-10-00-CN allows for the early detection of rotor instabilities, protecting high-value assets from catastrophic failure and optimizing maintenance intervals.

Suffix Logic Breakdown

The specific hardware configuration for this 3300 XL 25 mm probe is detailed below:

• 330851: Base model for the 3300 XL 25 mm Proximity Probe.

• 02 (Probe Case Type): Features a metric M30x2 threaded case for robust mounting.

• 000 (Unthreaded Length): 0 mm unthreaded portion; the case is fully threaded.

• 060 (Overall Case Length): Total housing length of 60 mm.

• 10 (Total Length): 1.0 meter (3.3 feet) integrated cable length.

• 00 (Armor Option): Standard cable without stainless steel armor.

• CN (Agency Approval): Includes specific regional hazardous area certifications for the Chinese market (NEPSI).

Technical Specifications

Technical FAQs

When should I choose a 25 mm probe over a standard 8 mm probe?The 25 mm probe is used when the expected target movement exceeds the 2.0 mm range of an 8 mm probe. It is ideal for measuring "Differential Expansion" on large turbines where the shaft grows significantly relative to the casing during thermal cycles.

Is this probe compatible with standard 3300 XL Proximitor sensors?No. The 330851 series must be used with a dedicated 3300 XL 25 mm Proximitor Sensor. The electrical characteristics and scale factor (20 mV/mil) differ significantly from standard 200 mV/mil systems.

Does the "No Armor" option affect the signal quality?The lack of armor (Option 00) does not impact electrical performance or signal integrity. However, it is recommended for installations where the cable is fully protected by conduit or located in areas with no risk of mechanical abrasion.

Engineering & Installation Guide

Calibration and Target MaterialThe 330851-02-000-060-10-00-CN is factory-calibrated for AISI 4140 steel. If your application involves a different shaft material, the scale factor may shift. Always perform a field calibration check using a spindle micrometer to verify the voltage-to-distance curve before finalizing the DCS/PLC alarm setpoints.

Gap Voltage SettingFor thrust and vibration measurements, the probe must be "gapped" correctly within its linear range. Typically, a gap voltage of approximately -10 VDC (center of the linear range) is desired. Use a high-impedance digital multimeter to measure the voltage at the Proximitor "OUT" and "COM" terminals during installation.

Chemical and Pressure ResistanceThe probe tip is constructed from PPS, which offers excellent resistance to most industrial lubricants and solvents. While rated for 13.8 bar, ensure that the O-ring seals on the M30 threads are compatible with the machine's oil type to prevent leaks at the mounting point.