Bently Nevada 330878-91-05 – 8mm Proximity Transducer Proximitor Sensor | 3300 XL Series Platform
Engineering Background: The Bently Nevada 3300 XL Series represents the industry benchmark for non-contacting eddy-current proximity measurement in rotating machinery protection systems. Deployed across power generation, oil & gas, petrochemical, and heavy industrial facilities worldwide, the 3300 XL platform delivers the signal integrity and long-term reliability that critical machinery monitoring demands.
Product Positioning: The 330878-91-05 is the Proximitor® Sensor (signal conditioner/driver) component of the 3300 XL 8mm proximity transducer system. It converts the raw oscillator signal from the probe into a calibrated DC voltage proportional to the gap between probe tip and target shaft — providing real-time vibration, position, and speed data to your monitoring system or DCS/PLC. This unit is engineered for procurement engineers who require a drop-in replacement or system expansion with full OEM specification compliance.
Complete Technical Specifications
| Part Number | 330878-91-05 |
| Brand / Manufacturer | Bently Nevada (Baker Hughes) |
| Series / Platform | 3300 XL 8mm Proximity Transducer System |
| Component Type | Proximitor® Sensor (Signal Conditioner) |
| Probe Compatibility | 3300 XL 8mm Proximity Probes (330780 series) |
| Extension Cable Compatibility | 3300 XL Extension Cables (330130 series) |
| Supply Voltage | -24 VDC (nominal) |
| Output Voltage Range | -1 VDC to -17 VDC |
| Scale Factor | 200 mV/mil (7.87 V/mm) |
| Linear Range | 0 to 80 mil (0 to 2.03 mm) |
| Frequency Response | DC to 10,000 Hz (–3 dB) |
| Operating Temperature | -35°C to +85°C |
| Enclosure / Housing | Aluminum alloy, IP65-rated |
| Connector Type | 2-pin MIL-spec connector |
| Approvals / Certifications | CE, FM, CSA, ATEX (consult datasheet for zone ratings) |
| Weight | Approx. 200 g |
| Country of Origin | USA |
Proven Application Environments
- Power Generation: Steam turbine, gas turbine, and hydro generator shaft vibration & eccentricity monitoring
- Oil & Gas: Compressor trains, centrifugal pumps, and expander-compressor units on upstream/midstream platforms
- Petrochemical & Refining: Critical rotating equipment in HAZLOC environments requiring ATEX/FM-rated sensors
- Pulp & Paper / Steel: High-speed roll and fan shaft monitoring in continuous process lines
- Marine & Offshore: Propulsion shaft and auxiliary machinery protection systems
- General Industrial: Any application requiring API 670-compliant non-contacting vibration measurement
Engineering Advantages
- API 670 Compliant: Meets the machinery protection standard for critical rotating equipment — no re-qualification required for existing installations
- Eddy-Current Technology: Non-contacting measurement eliminates mechanical wear; immune to oil, steam, and most process contaminants
- Wide Frequency Bandwidth (DC–10 kHz): Captures both low-speed eccentricity and high-frequency blade-pass events in a single channel
- Stable Scale Factor: 200 mV/mil factory-calibrated output integrates directly with Bently Nevada 3500/3300 monitors and third-party DCS/PLC analog input cards
- Rugged IP65 Housing: Suitable for outdoor and wash-down environments without additional enclosure
- Long-Term OEM Support: Active part number within the Baker Hughes / Bently Nevada portfolio — spare parts and calibration services available
System Architecture & Signal Flow
The 3300 XL 8mm system operates as a three-component eddy-current chain:
- Probe (330780-xx-xx): Mounted in the bearing housing; generates a high-frequency electromagnetic field directed at the rotating shaft target area.
- Extension Cable (330130-xx-xx): Transmits the oscillator signal from probe to Proximitor with controlled impedance; total system cable length must match calibrated range.
- Proximitor Sensor 330878-91-05 (this unit): Receives the oscillator signal, demodulates it, and outputs a calibrated –1 to –17 VDC signal. This output connects directly to the monitor rack (e.g., Bently Nevada 3500/22M or 3300/16) or to a PLC/DCS analog input module.
Note: All three components must be from the same calibrated system family (3300 XL 8mm) to maintain specification accuracy. Mixing probe/cable/Proximitor from different series will invalidate calibration.
Sourcing & Quality Verification
- Units sourced from authorized distributors, OEM surplus, and verified industrial decommissions
- Each unit undergoes visual inspection, connector integrity check, and functional output verification prior to shipment
- Part number label, date code, and housing markings are photographically documented — images available on request
- Traceability documentation (COC / test report) available for critical plant applications
- Konmask.com maintains a no-counterfeit policy: units failing authentication are quarantined and not listed for sale
Procurement Process
- Confirm compatibility: Verify your existing probe (330780 series) and extension cable (330130 series) are 3300 XL 8mm family
- Request quote: Contact support@konmask.com for volume pricing, lead time, and documentation requirements
- Place order: Purchase order accepted via email; proforma invoice issued within 1 business day
- Shipping: DHL / FedEx Express international; EXW Xiamen, China. Typical transit: 3–7 business days
- After-sales: 90-day warranty on verified functional units; RMA process available
Technical FAQ
Q: Is the 330878-91-05 compatible with the older 3300 (non-XL) probe series?
A: No. The 3300 XL 8mm system uses a different oscillator frequency and impedance than the legacy 3300 series. Mixing components will result in out-of-specification output. Always match probe, cable, and Proximitor within the same series.
Q: Can this Proximitor drive a 4–20 mA input directly?
A: No. The output is –1 to –17 VDC. A signal conditioner or the Bently Nevada 3500 monitor’s I/O module is required to convert to 4–20 mA for DCS integration.
Q: What is the maximum total cable length for this system?
A: The 3300 XL 8mm system is calibrated for a specific probe + cable length combination. Standard configurations are 5m, 9m, and 15m total. The Proximitor part number suffix (-05 in 330878-91-05) indicates the calibrated cable length — confirm with your system documentation.
Q: Do you provide calibration certificates?
A: Functional verification reports are available. Factory NIST-traceable calibration certificates are available for new/unused OEM stock. Contact us to confirm availability for your specific unit.
Q: Can I order in bulk for a plant turnaround?
A: Yes. We maintain stock for turnaround and MRO procurement. Contact support@konmask.com with your BOM and required delivery date.
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