Bently Nevada 330905-00-09-05-01-00 Proximity Probe – 3300 XL Series

Bently Nevada 330905-00-09-05-01-00 — 9mm Eddy Current Proximity Probe with 5-Metre Integral Cable for 3300 XL Machinery Protection Systems

The 330905-00-09-05-01-00 is a 9 mm-body eddy current proximity probe manufactured by Bently Nevada (Baker Hughes) for deployment within the 3300 XL continuous machinery protection platform. Its primary function is non-contact, DC-coupled measurement of rotor radial displacement and shaft axial position in rotating equipment operating under API 670 5th Edition protection mandates. The probe constitutes the first stage of a three-element measurement chain — probe, extension cable, and Proximitor® sensor — and its electrical characteristics are factory-calibrated as a matched system to deliver a nominal scale factor of 7.87 V/mm (200 mV/mil) against AISI 4140 steel targets.

In a closed-loop machinery protection architecture, this probe feeds a continuous DC voltage signal proportional to the instantaneous air gap between the probe tip and the rotating shaft surface. That signal is processed by the downstream 3300 XL Proximitor® sensor, which demodulates the carrier frequency and outputs a conditioned DC voltage to the 3500 or 3300 monitor rack. The rack executes alarm and trip logic in hardware, providing deterministic response times independent of host SCADA polling cycles — a critical requirement for turbine overspeed and compressor surge protection circuits.

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Technical Parameters

Hardware Logical Analysis

The 330905-00-09-05-01-00 operates on the eddy current induction principle. An oscillator circuit within the Proximitor® sensor drives a high-frequency alternating current — typically in the range of 1.0 to 1.5 MHz — through the coil wound inside the probe tip. This energized coil generates a localized electromagnetic field that penetrates the conductive shaft surface. As the shaft surface enters the field, eddy currents are induced within the target material, creating a counter-magnetic field that loads the probe coil and reduces its effective inductance and Q-factor. The Proximitor® sensor detects this impedance change and converts it to a proportional DC output voltage.

The 9 mm probe body geometry is a deliberate design choice for installations where bearing housing bore constraints preclude the larger 11 mm or 25 mm probe bodies. The M10 × 1 thread pitch provides fine positional adjustment during gap-setting procedures, allowing technicians to achieve the nominal –10.5 VDC bias voltage at the 1.27 mm (50 mil) target gap with sub-millimetre precision before locknut torquing.

The 5-metre integral armored cable is factory-calibrated as part of the probe assembly. The cable’s distributed capacitance and inductance are accounted for in the Proximitor® sensor’s internal compensation network. Substituting a field-spliced or non-OEM cable of differing impedance characteristics will shift the scale factor and bias voltage, introducing systematic measurement error that may not be immediately apparent during commissioning but will degrade alarm setpoint accuracy over time.

EMC performance is achieved through the coaxial cable construction with continuous foil and braid shielding, terminated to chassis ground at the Proximitor® sensor end. The probe body itself is constructed from 316 stainless steel, providing corrosion resistance in wet or chemically aggressive environments while maintaining dimensional stability across the rated temperature range. The IP67 rating ensures the probe body and cable junction can withstand temporary immersion, relevant in lube oil mist environments common in turbine bearing pedestals.

The DC-to-10,000 Hz frequency response is sufficient to capture all rotor dynamic phenomena of engineering significance: synchronous (1×) and sub-synchronous vibration components, oil whirl instability (typically 0.43–0.48× running speed), and structural resonances in the lower acoustic range. The flat DC response also enables static position measurement for thrust position and differential expansion monitoring without the low-frequency rolloff that would affect AC-coupled sensors.

System Integration Benefits

• Deterministic alarm response: The probe-to-Proximitor®-to-monitor signal chain operates entirely in analog hardware up to the monitor rack’s comparator stage, delivering trip relay actuation within milliseconds of a threshold crossing — independent of PLC scan cycles or network latency.
• Direct 3300 XL and 3500 rack compatibility: The 330905 probe is electrically and mechanically interchangeable within existing 3300 XL Proximitor® sensor loops, enabling like-for-like replacement without monitor reconfiguration or scale factor adjustment.
• Calibrated system traceability: Each probe carries a unique serial number linked to factory calibration records. This supports ISO 17025-aligned maintenance documentation and satisfies audit requirements in regulated industries including nuclear, petrochemical, and power generation.
• Dual-function measurement capability: A single probe installation can simultaneously provide radial vibration data (AC component) and shaft centerline position data (DC component) to the monitor rack, reducing the number of penetrations required in bearing housings.
• Wide operating temperature margin: The +177 °C upper limit provides a 40–60 °C thermal margin above typical steam turbine bearing housing temperatures, preventing sensor drift or failure during transient thermal events such as lube oil system upsets.
• Non-contact measurement eliminates wear mechanisms: Unlike contact-type displacement transducers, the eddy current probe has no moving parts and imposes zero mechanical load on the shaft. Mean time between replacement is governed by environmental degradation rather than mechanical fatigue.
• Integral cable eliminates field termination variability: Factory-terminated 5 m cables remove the measurement uncertainty introduced by field-made coaxial connections, which are a known source of impedance discontinuities and intermittent signal faults in high-vibration environments.
• Broad target material compatibility with correction factors: While calibrated for AISI 4140 steel, the probe can be applied to shafts of 316 stainless, Inconel 718, and titanium alloys using published material correction factors, extending applicability to aerospace and advanced process equipment without hardware modification.

Quality Assurance & Global Logistics

Every 330905-00-09-05-01-00 unit supplied by siemensplc.com is sourced through verified channels with full serialization and incoming inspection. Each probe undergoes bias voltage verification at the nominal 1.27 mm gap, visual inspection of the probe tip and cable jacket, and connector continuity testing prior to dispatch. Units are packaged in anti-static foam with moisture barrier film and silica gel desiccant to maintain storage integrity during international transit.

Shipments originate from our warehouse in Xiamen, China — a major logistics hub with direct access to international air freight and sea freight services. Standard in-stock orders are dispatched within 1–3 business days. Express air freight to Europe, North America, Southeast Asia, and the Middle East typically achieves door-to-door delivery within 3–7 business days. Sea freight consolidation is available for volume orders requiring cost-optimized routing.

Documentation packages available upon request include: Certificate of Conformance (CoC), factory test reports, packing lists with serial numbers, and commercial invoices formatted for customs clearance. All units are shipped with a 12-month warranty covering manufacturing defects under normal operating conditions.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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