Product Overview

The Bently Nevada 26530-12-10-03-018-225-22-04-00 Dual Probe Transducer System combines a 3300 XL 8 mm proximity probe with a high-temperature, two-wire Seismoprobe. This integrated arrangement is used in rotating machinery monitoring applications where shaft movement relative to its mounting point and vibration of the supporting structure need to be evaluated together.

The proximity probe measures changes in the gap between its sensing tip and the conductive shaft surface. This measurement provides information about shaft position and dynamic movement relative to the probe mounting point. The Seismoprobe measures vibration of the bearing housing or machine casing, supplying a separate indication of structural movement.

These measurements serve different purposes in machinery diagnostics. A rotor may move relative to its bearing while the bearing housing vibrates in response to mechanical forces. The proximity channel captures the relative shaft movement, while the seismic channel records the supporting structure’s vibration. Evaluating both signals helps engineers distinguish changes in rotor behavior from changes in casing motion.

The 26530-12-10-03-018-225-22-04-00 configuration incorporates a 1-meter probe lead, a 3/4-14 NPT adapter connection, an 018 adapter-length option, and a 225 probe-penetration option. The assembly also specifies the high-temperature, two-wire Seismoprobe, a single 3/4-14 NPT plug fitting, and no optional probe support/oil seal.

The extended probe penetration suits installations where the measurement target is positioned deep inside a bearing housing or machine casing. The mounting arrangement must allow the probe to reach the intended shaft surface while maintaining the required sensing gap. Mechanical rigidity is also important because movement or resonance in the mounting assembly can influence the measurement signal.

The combined arrangement supports shaft relative radial position, shaft relative radial dynamic motion, machine-casing absolute vibration, and shaft absolute motion calculated through appropriate signal processing. The last measurement requires compatible monitoring equipment capable of processing the seismic and relative-displacement signals together.

In industrial compressors and steam turbines, these measurements can help maintenance teams investigate vibration changes during startup, speed transitions, and changing operating loads. Comparing the shaft-relative and casing-vibration trends provides more diagnostic context than examining either measurement independently.

The assembly functions as part of a larger machinery monitoring installation. Signal conditioning, correct sensor positioning, suitable electrical connections, and appropriate monitoring-channel configuration are necessary for meaningful results. The transducer assembly supplies measurement signals; machinery protection and alarm functions depend on the connected monitoring system.

Technical Specifications

Product Features

• Integrated dual sensing: Combines shaft-displacement measurement and structural vibration sensing in one assembly.
• 3300 XL 8 mm proximity probe: Measures shaft displacement relative to the probe mounting point.
• High-temperature Seismoprobe: Captures vibration of the supporting structure through a two-wire sensing arrangement.
• Extended probe penetration: Accommodates measurement locations requiring a longer probe reach.
• NPT mounting connection: Uses a 3/4-14 NPT adapter interface.
• Defined probe lead: Incorporates the specified 1-meter probe lead.
• Complementary measurement channels: Separates shaft-relative movement from casing vibration.
• Combined motion analysis: Supports shaft absolute-motion calculations through compatible monitoring equipment.
• Rotating machinery integration: Supplies signals for machinery condition-monitoring installations.

Working Principle

The Bently Nevada 26530 Dual Probe Transducer System combines eddy-current proximity sensing with seismic vibration measurement. Each sensor responds to a different type of machine movement, allowing the connected monitoring equipment to evaluate shaft behavior and supporting-structure vibration separately.

The 3300 XL 8 mm proximity probe generates an electromagnetic field that interacts with the conductive shaft surface. As the gap between the probe tip and shaft changes, the electrical response changes accordingly. Compatible signal-conditioning equipment converts this response into a displacement measurement relative to the probe mounting point.

The high-temperature, two-wire Seismoprobe measures vibration of the supporting structure. Its output represents casing or bearing-housing vibration rather than the shaft-to-probe gap. This additional signal is useful when the structure supporting the proximity probe is itself moving.

Shaft Surface → 3300 XL 8 mm Probe → Relative Displacement Signal

Bearing Housing → High-Temperature Seismoprobe → Structural Vibration Signal

Compatible Monitoring Equipment → Signal Processing → Shaft Absolute-Motion Assessment

The proximity channel supplies information about shaft-relative position and dynamic movement. The seismic channel measures structural vibration. When the monitoring system integrates the seismic velocity signal into displacement and combines it appropriately with the relative shaft-displacement signal, it can calculate shaft absolute motion.

For example, a compressor may experience increased vibration as its operating load changes. The rotor can move relative to the bearing while the housing responds to the same operating conditions. The proximity probe captures the relative shaft movement, and the Seismoprobe records housing vibration. Examining both measurements helps engineers determine which movement patterns require further investigation.

The extended penetration configuration affects the mechanical installation. The probe must reach the intended conductive target without interference from surrounding components. Its sensing gap must be adjusted correctly, and the mounting arrangement must remain sufficiently rigid to avoid introducing unwanted motion into the measurements.

The Seismoprobe’s mounting orientation and frequency characteristics must also suit the application. The specified configuration has an orientation range of 0° ± 100° and a minimum operating frequency of 600 cpm. These characteristics should be considered when selecting the measurement point and assessing data across the machine’s operating range.

The assembly does not independently diagnose faults or initiate a machinery shutdown. Fault identification, alarm decisions, and protective actions depend on the connected monitoring equipment, signal processing, configured alarm limits, and the wider machinery protection system.

Role in a Rotating Machinery Monitoring System

The Bently Nevada 26530-12-10-03-018-225-22-04-00 provides complementary measurements for rotating machinery monitoring. Its proximity channel follows shaft movement relative to the mounting point, while its velocity channel measures vibration of the supporting structure.

Shaft Movement → Proximity Measurement

Casing Vibration → Seismic Measurement

Monitoring Channels → Signal Processing → Operator Display and Alarm Logic

For radial-bearing diagnostics, two suitable assemblies can be installed along perpendicular X-Y axes. With appropriately configured monitoring equipment, this arrangement supports shaft orbit analysis and shaft centerline evaluation using measurements from both radial directions.

Industrial Applications

Installation and Maintenance

1. Confirm the measurement location: Select a mounting point that provides access to the intended shaft target and a suitable mechanical reference on the bearing housing or casing.
2. Check the adapter interface: Confirm that the machine mounting provision matches the specified 3/4-14 NPT adapter connection.
3. Review the mounting geometry: Account for the 1.8-inch adapter-length option and the specified probe-penetration configuration when checking the installation drawing and available clearance.
4. Inspect the target surface: Ensure the shaft surface is suitable for eddy-current measurement and that the probe faces the intended measurement area.
5. Set the probe gap: Establish the initial clearance according to the applicable 3300 XL 8 mm installation procedure and the requirements of the connected signal-conditioning equipment.
6. Secure the assembly: Tighten the mounting hardware according to the applicable installation requirements to prevent unwanted movement of the sensor housing during operation.
7. Inspect the probe lead: Check the 1-meter lead for cuts, crushing, abrasion, and excessive strain before connecting the electrical circuit.
8. Connect the velocity transducer: Follow the wiring requirements for the high-temperature, two-wire Seismoprobe and its compatible receiving input.
9. Check sensor orientation: Position the velocity transducer within its specified orientation range and ensure the measurement axis matches the intended monitoring function.
10. Verify signal conditioning: Confirm that the proximity and velocity signals are connected to suitable inputs with the correct scaling and measurement configuration.
11. Assess mechanical support: Check the extended probe mounting arrangement for adequate rigidity and potential resonance that could affect the measurement signals.
12. Establish baseline readings: Record shaft-relative displacement and casing vibration under known operating conditions, then compare subsequent readings against these baseline measurements.

During maintenance, inspect the probe gap, mounting security, lead condition, and electrical connections. If the proximity and velocity signals exhibit different trends, investigate the two measurement paths separately before attributing the change to rotor behavior or structural vibration.

Related Components

Recommended Related Models

Key Advantages

• Combines shaft-relative displacement and casing-vibration measurements in one assembly.
• Helps distinguish rotor movement from motion of the supporting structure.
• Uses a 3300 XL 8 mm proximity probe and a high-temperature, two-wire Seismoprobe.
• Supports shaft absolute-motion assessment through compatible signal processing.
• Accommodates an extended probe-penetration arrangement.
• Supplies complementary measurement data for rotating machinery diagnostics.

Technical FAQs

How can the two sensor signals help distinguish rotor movement from casing vibration?

The proximity probe measures shaft movement relative to its mounting point, while the Seismoprobe measures vibration of the supporting structure. Comparing the signals helps compatible monitoring equipment distinguish relative shaft motion from casing vibration and calculate shaft absolute motion where supported.

What installation factors matter for an extended probe-penetration arrangement?

The mounting geometry must allow the probe to reach the intended shaft target while maintaining the correct sensing gap. Available clearance, mounting rigidity, and potential mechanical resonance also need to be considered when installing an extended probe arrangement.

What role does the high-temperature Seismoprobe play in this assembly?

The Seismoprobe supplies a structural vibration measurement that complements the proximity probe’s shaft-displacement signal. Its operating environment, mounting orientation, and electrical connection must be suitable for the specified sensor configuration and connected monitoring input.

What is required to perform radial shaft orbit analysis with this system?

Comprehensive radial-bearing orbit analysis generally requires two suitable assemblies positioned along perpendicular X-Y axes. The connected monitoring equipment must be configured to process the corresponding measurements and display the resulting orbit data.