330876-02-50-01-05 Bently Nevada 50mm Proximity Sensor

Overview

The 330876-02-50-01-05 is a heavy-duty 3300 XL 50 mm eddy current proximity probe engineered by Bently Nevada specifically for large steam turbine differential expansion (DE) monitoring. Constructed with a Polyphenylene Sulfide (PPS) tip, AISI 304 stainless steel threaded body, and high-temperature FluidLoc triaxial cable, this sensor withstands continuous operating temperatures up to 200°C (392°F) and short-term thermal spikes up to 250°C (482°F).

Features on the 330876-02-50-01-05 include dual front/rear environmental seals, flexible stainless steel armor, high-temperature ClickLoc connectors with removable collars, and pre-drilled M14x1.5 locknuts. Its integrated 5.0-meter cable connects directly to a matching 5-meter 3300 XL 50 mm Proximitor sensor without inter-cable extension loss.

Configuration Breakdown: 330876-02-50-01-05

• Base Model: 330876 — 3300 XL 50 mm Proximity Transducer
  • [-02] Probe Case Type: Straight Exit Case with M14x1.5 Metric Threads (21 mm Max Thread Engagement)
    • [-50] Total Length Option: 5.0 Meters (16.4 feet) Integrated System Length
  • [-01] Armor Option: High Temperature FluidLoc Cable with Flexible Stainless Steel Armor
    • [-05] Agency Approval Option: Multiple International Hazardous Area Approvals (CSA, ATEX, IECEx)

Technical Specifications & Environmental Limits

Cross-Model Specification Comparison & Engineering Guidance

Engineering Selection Strategy:

• Mounting Spatial Requirements: The M14x1.5 metric straight case (-02) provides fine axial thread positioning through machine casing walls. If radial clearance behind the turbine housing is tight, choose side-exit bracket models like the 330876-03-90-01-00 to route cables perpendicular to the target.
• Cable Length Matching: Suffix -50 (5.0m) connects directly to a 5-meter Proximitor without extension cables, reducing signal connection points. Ensure your Proximitor sensor part number matches the probe cable length rating (5m probe with 5m Proximitor).

Target Machinery & Industrial Application Environments

• Utility Steam Turbine Generators: Rotor-to-stator differential expansion measurement across high-pressure (HP) and intermediate-pressure (IP) turbine casings.
• Nuclear Power Turbomachinery: Long-range linear shaft displacement tracking subject to high thermal expansion cycling and steam ingress.
• Large Gas Turbines: Thermal casing growth and axial thrust position monitoring in hazardous division power plants.
• Industrial Boiler Feed Drives: Rotor position surveillance in wet, high-temperature condensate environments.

Diagnostic Features & Electrical Inspection

• FluidLoc triaxial cable construction blocks high-pressure steam condensate from wicking along internal cable strands into junction boxes.
• ClickLoc gold-plated connectors feature removable collars to facilitate pulling cable runs through tight conduit elbows without pin damage.
• Allows field verification of coil integrity using a digital multimeter; normal center-to-coaxial resistance measures exactly 7.6 ± 0.8 Ω at room temperature.
• Delivers an extended linear dynamic range (up to 50 mm) for tracking large mechanical growth without sensor saturation or scale wrapping.

Global PLC Spare HUB's Insight

When installing 50 mm differential expansion probes like the 330876-02-50-01-05, mechanical alignment relative to the target collar edge is critical. Because a 50 mm tip projects a wide electromagnetic field, installing the probe tip within 75 mm of adjacent structural steel or machine ribs causes side-loading field attenuation, distorting the linear scale curve of the 3300 XL Proximitor sensor.

During a steam turbine overhaul, site engineers reported non-linear output readings on a newly fitted 330876-02-50-01-05 transducer. Our technical check revealed that the M14x1.5 body was threaded through an un-counterbored steel bracket, causing the 1.99-inch sensor head to sit too close to the mounting frame. Re-machining the clearance pocket to maintain a minimum 100 mm radial clearance around the PPS tip eliminated stray eddy current loading, restoring clean -200 mV/mm linear scale accuracy across the entire differential expansion range.

Logistics, Handling & Warranty Terms

• Supply Condition: Delivered 100% brand-new and original in sealed factory Bently Nevada packaging.
• Factory Warranty: Covered by a full 12-month replacement warranty effective from ship date.
• Express Global Courier: Expedited international shipping via priority service with FedEx, UPS, and DHL.
• Order Fulfillment: Factory inventory dispatched from warehouse within 24 to 48 hours following order confirmation.

Engineering Selection FAQ

Why is matching the 5.0-meter probe cable directly to a 5-meter Proximitor sensor required?

The total electrical length of the probe cable forms an integral part of the resonant LC tank circuit inside the Proximitor sensor. Connecting a 5m probe to a 9m Proximitor changes the circuit inductance, causing severe scale factor errors.

What is the advantage of FluidLoc cable technology on steam turbine applications?

FluidLoc cable features internal PFA insulation barriers that prevent steam, moisture, and synthetic oils from traveling through the interior of the cable sheath if the outer jacket is cut or compromised in service.

How can a field technician verify if a 330876 probe coil has suffered thermal degradation?

Measure the DC resistance between the center conductor and outer coaxial conductor using a calibrated multimeter. Standard resistance is 7.6 ± 0.8 Ω; readings above 10 Ω or short circuits indicate thermal breakdown inside the PPS tip assembly.

Does the M14x1.5 thread option require a specific installation torque?

Yes, do not exceed 20 N·m (15 ft-lbs) of mounting torque on the M14x1.5 casing thread. Always secure the included pre-drilled locknut with stainless steel safety wire to prevent loosening under heavy machine vibration.

Can the ClickLoc connector collar be removed during cable pull through tight conduits?

Yes, the ClickLoc connector includes a removable collar that unclips to reduce the overall connector diameter, allowing the cable to slide smoothly through narrow conduit runs without snagging internal walls.

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