Bently Nevada 330195-02-12-10-CN 3300 XL 8 mm Extended Temperature Range (ETR) Reverse Mount Probe

Product Overview

The Bently Nevada 330195-02-12-10-CN is a specialized 8 mm eddy current proximity probe part of the 3300 XL Extended Temperature Range (ETR) series. This transducer is specifically engineered for reverse mount applications where the probe must be installed from the interior of a machine housing or through a probe sleeve. The ETR version is rated for significantly higher operating temperatures than standard probes, making it the primary choice for monitoring radial vibration and axial position in steam turbines, gas turbines, and other high-heat rotating machinery.

This specific model features a 3/8-24 UNF thread and is configured with a 1.0-metre (3.3 feet) total cable length. The "CN" suffix denotes compliance with country-specific hazardous area certifications, including NEPSI approvals for the Chinese market. When integrated with a 3300 XL ETR extension cable and Proximitor sensor, the system delivers a stable linear scale factor of 7.87 V/mm (200 mV/mil) even under extreme thermal cycling conditions.

Technical Configuration

Ordering Information

Reverse mount probes are distinct from standard mount probes in their mechanical housing. Ensure the part number matches the internal machine clearances and the corresponding Proximitor sensor calibration.

Engineering & Installation Notes

Reverse Mount Considerations:

Unlike standard probes, the 330195 series is designed to be threaded into a housing from the "back." This is typically required when using Bently Nevada probe housing assemblies or when internal machine space prevents standard front-side access. Ensure that the internal cable routing does not exceed the minimum bend radius of 25.4 mm (1.0 in) to prevent coaxial signal degradation.

Thermal Expansion Management:

The Extended Temperature Range (ETR) probes are designed for environments up to 260°C (500°F). When gapping the probe at ambient temperature, engineers must account for the thermal expansion of the machine shaft and housing. Failure to calculate the "hot gap" can result in the probe tip making contact with the shaft (rubbing) or moving out of the linear range during operation.

Cable Integrity in High-Heat Zones:

The 1.0-metre integral cable is rated for the same temperature as the probe tip. However, where the cable exits the high-temperature zone and connects to the extension cable, the ClickLoc™ junction should be housed in a dry, protected location. Use of silicone connector protectors is mandatory in oil-mist environments to prevent fluid "wicking" into the coaxial core, which causes signal drift.

Grounding & Shielding:

Maintain a single-point ground. The coaxial shield should be grounded only at the Proximitor end (usually at the monitor rack). In high-interference environments typical of gas turbine halls, ensure the extension cable is routed through a dedicated, grounded conduit to maintain a high signal-to-noise ratio.

Troubleshooting FAQ

Q: Can I use a standard 3300 XL extension cable with this ETR probe?

A: While they are physically compatible, for maximum accuracy at high temperatures, you must use a 3300 XL ETR extension cable. Standard cables may not withstand the heat or provide the necessary temperature compensation.

Q: How do I verify the gapping on a reverse-mount probe?

A: Use a digital voltmeter at the Proximitor output terminals. For a 3300 XL system, the mid-range gap is typically reached at -10.0 Vdc. Adjust the probe position within the reverse mount sleeve until this value is stabilized.

Q: What indicates a temperature-related probe failure?

A: If the DC gap voltage drifts significantly as the machine warms up, but the shaft position is known to be stable, the sensing coil or the coaxial junction may be failing due to thermal stress.

Q: What is the difference between standard "02" and "CN" approvals?

A: Functionally, the probes are identical. The "CN" version is specifically labeled and documented to meet the regulatory import and safety requirements of the People's Republic of China (NEPSI).