Bently Nevada 330104-01-07-10-02-00 Proximity Transducer – 3300 XL

330104-01-07-10-02-00: Matched-Set Eddy-Current Transducer System for Rotating Machinery Protection

The Bently Nevada 330104-01-07-10-02-00 is a factory-calibrated, three-component proximity transducer assembly belonging to the 3300 XL product family. The system comprises an 8 mm eddy-current probe, a 7 ft (2.134 m) armored coaxial probe cable, and a 10 ft (3.048 m) extension cable terminated at a 3300 XL Proximitor® sensor. These three elements are serialized and calibrated as a single measurement chain at the factory; substituting any individual component from a different calibration batch introduces a systematic scale factor error that cannot be corrected through monitor rack configuration alone.

The operating principle is inductive eddy-current displacement sensing. The Proximitor® sensor drives a continuous 1.0 MHz sinusoidal excitation signal through the coaxial cable assembly to the probe tip coil. When a conductive target surface — typically a machined journal or thrust collar — enters the probe’s near-field electromagnetic zone, the alternating magnetic flux induces circulating eddy currents in the target material. These eddy currents present a resistive load that damps the probe coil’s Q-factor, reducing the oscillator amplitude in proportion to the probe-to-target gap. The Proximitor® demodulates this amplitude-modulated carrier into a DC-coupled analog voltage at a calibrated sensitivity of 200 mV/mil (7.87 V/mm), with a linear measurement range spanning 10 to 90 mil (0.25 to 2.29 mm). The output is a negative-going voltage: a gap of 10 mil produces approximately −2 VDC; a gap of 90 mil produces approximately −18 VDC, referenced to the −24 VDC supply rail.

The part number structure encodes the complete system configuration with no ambiguity. The base model 330104 identifies the 3300 XL 8 mm probe family. The first suffix 01 specifies the standard flat-face probe tip geometry, optimized for target diameters ≥ 50 mm. The second suffix 07 encodes the 7 ft probe cable; 10 encodes the 10 ft extension cable. The fifth field 02 designates armor-jacketed cable construction with continuous RF shielding. The final field 00 specifies the standard reverse-mount coaxial connector termination. This encoding scheme allows maintenance engineers to verify system configuration from the part number alone, without reference to installation drawings.

Typical deployment contexts include radial vibration measurement at journal bearings on steam and gas turbines, axial position monitoring on centrifugal compressors and boiler feed pumps, differential expansion measurement on large steam turbine casings, and shaft eccentricity surveillance on slow-roll gearboxes. The system is fully compliant with API 670 Fifth Edition, the mandatory instrumentation standard for machinery protection systems in critical service applications across oil and gas, power generation, and petrochemical industries. Hazardous area certifications include FM Class I Division 1 Groups A–D, ATEX II 1G Ex ia IIC T4 Ga, and IECEx, permitting installation in Zone 0 and Zone 1 classified atmospheres when used with an appropriate intrinsic safety barrier in the supply circuit.

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Technical Parameters

Hardware Logical Analysis

Three hardware-level design decisions in the 3300 XL architecture directly determine measurement accuracy and long-term reliability in industrial environments.

Oscillator Frequency Stability and Scale Factor Traceability: The Proximitor® sensor’s internal LC oscillator uses components selected for matched temperature coefficients of capacitance and inductance. Across the full −35°C to +85°C operating envelope, oscillator frequency deviation is held within ±0.5%. This matters because the demodulated output sensitivity is a direct function of oscillator frequency: a 1% frequency shift produces a proportional 1% scale factor error. At the 2.29 mm upper end of the linear range, a 1% error represents 22.9 µm of false displacement — sufficient to mask early-stage bearing wear or trigger nuisance alarms in tightly toleranced machinery protection setpoints. The factory calibration dataset, unique to each matched set’s serial number, captures the actual scale factor at 25°C and provides temperature correction coefficients for use in precision measurement applications.

Coaxial Cable Impedance Control and Matched-Set Architecture: The coaxial cable assembly is manufactured to a controlled characteristic impedance of 50 Ω ± 2 Ω, with cable capacitance per unit length held within ±5% of the nominal value. The Proximitor® oscillator circuit is designed to drive a specific total cable capacitance load — the sum of probe cable and extension cable capacitances — that corresponds to the calibrated cable lengths encoded in the part number. Substituting a cable of different length or construction changes the total capacitive load on the oscillator tank circuit, shifting the effective Q-factor and altering the probe’s sensitivity curve in a nonlinear manner that cannot be corrected by a simple gain adjustment in the monitor rack. The matched-set architecture eliminates this variable entirely by fixing the cable configuration at the calibration stage.

RF Shielding and EMC Performance: The armor-jacketed cable construction provides a continuous Faraday shield from the probe tip connector to the Proximitor® housing. The reverse-mount connector geometry ensures that the outer shield conductor is terminated before the center conductor at both ends of the cable run, eliminating any exposed coaxial section that could function as a receiving antenna. Measured RF attenuation through the shield exceeds 40 dB across the 100 kHz to 1 GHz band. In installations where the transducer cable runs parallel to variable frequency drive (VFD) output conductors or high-current bus bars — common in compressor station and turbine hall environments — this shielding level prevents common-mode interference from coupling into the 1.0 MHz carrier signal. Unshielded or inadequately shielded cables in such environments produce spurious spectral components in the demodulated vibration signal that are indistinguishable from real sub-synchronous rotor instabilities, leading to incorrect diagnostic conclusions.

Probe Tip Field Geometry and Target Size Constraints: The 8 mm probe face generates an eddy-current sensing field with an effective diameter of approximately 16 mm (2× probe diameter). The standard tip geometry encoded as “01” is optimized for flat or convex target surfaces with a minimum target diameter of 16 mm. For shaft diameters below 50 mm, the curvature of the target surface causes the eddy-current field to partially wrap around the shaft, introducing a nonlinearity at the extremes of the linear range. API 670 Annex D provides the curvature correction methodology for such installations; the 330104-01-07-10-02-00 is compatible with this correction procedure without hardware modification.

System Integration Benefits

• Zero-Conditioning Signal Path: The −2 to −18 VDC output interfaces directly with Bently Nevada 3500/40M, 3500/42M, 3500/46M, and 3300 series monitor input cards. No interposing isolators, impedance converters, or signal conditioners are required between the Proximitor® and the monitor rack, removing four to six potential failure points per channel from the signal chain.
• Unified DC-to-10 kHz Measurement Bandwidth: A single channel simultaneously captures quasi-static shaft position (DC component, used for axial position and gap monitoring) and dynamic vibration up to 10,000 Hz (AC component, used for vibration amplitude and spectral analysis). This eliminates the need for parallel AC-coupled and DC-coupled measurement paths that some alternative transducer platforms require.
• Gap Channel Diagnostics Without Machine Shutdown: The DC gap voltage is continuously available as a separate monitor channel in the 3500 rack. Trending this value over time reveals probe fouling by process deposits, gradual shaft centerline migration due to bearing wear, and thermal growth of the machine casing — all detectable without interrupting machine operation or requiring physical access to the transducer installation.
• API 670 Compliance Eliminates Re-qualification: Specifying an API 670-compliant transducer system removes the engineering review and qualification testing cycle that plant safety authorities require for non-standard instrumentation. On a typical greenfield installation, this reduces instrumentation acceptance time by two to four weeks and eliminates the cost of third-party qualification testing.
• Intrinsic Safety Certification for Classified Areas: FM, ATEX, and IECEx certifications allow direct installation in Zone 1 / Division 1 classified atmospheres. When used with a certified IS barrier (e.g., MTL 787+ or equivalent) in the Proximitor® supply circuit, the system meets Zone 0 / Division 1 requirements, avoiding the cost and installation complexity of explosion-proof conduit and junction box systems.
• Drop-In Replacement Compatibility: The 330104-01-07-10-02-00 is a direct replacement for any existing 3300 XL 8 mm matched-set installation with identical cable lengths. Monitor rack alarm and trip setpoints, scale factor configuration, and gap reference values require no adjustment upon replacement, provided the replacement unit carries the same factory calibration dataset. Planned maintenance outage time for a single-channel transducer replacement is typically under 30 minutes.
• Multi-Channel Rack Density: The 3500/42M monitor card accepts two proximity transducer input channels per card slot. A complete four-bearing turbine-generator train — eight radial vibration channels plus two axial position channels — requires five monitor cards in a single 3500 rack, minimizing rack footprint and inter-card wiring complexity in space-constrained control rooms.
• Extended Asset Lifecycle Support: The 3300 XL platform has been in continuous production and active support since the early 1990s. Bently Nevada maintains spare parts availability commitments aligned with the 20–30 year operational life of the rotating machinery assets these systems protect. This eliminates the obsolescence risk and forced platform migration costs associated with discontinued transducer families.

Quality Assurance & Global Logistics

Each 330104-01-07-10-02-00 unit dispatched from our Xiamen, China facility passes a structured incoming inspection protocol before packaging. Inspection steps include: visual verification of OEM labeling, serial number, and date code against manufacturer records; functional gap voltage linearity test across the full 10–90 mil range using a calibrated AISI 4140 steel target plate; matched-set serial number cross-check confirming that probe, extension cable, and Proximitor® serial numbers correspond to a single factory calibration record; coaxial connector contact resistance measurement to OEM specification; and continuity verification of the armor shield from probe tip to Proximitor® housing.

Units are packaged in anti-static foam-lined enclosures with a humidity indicator card and silica gel desiccant pouch. Outer cartons are rated for air freight vibration and shock per ISTA 2A. Standard air freight transit times from Xiamen are 3–5 business days to Europe and North America, and 2–3 business days to Southeast Asia and the Middle East. DHL Express, FedEx International Priority, and UPS Worldwide Express are available. Export documentation — commercial invoice, packing list, and Certificate of Conformance — is prepared to HS Code 9031.80 customs clearance standards. A 12-month warranty against manufacturing defects is provided with every unit.

Contact Information

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