Bently Nevada 24701-28-05-00-026-04-02 3300 XL Retrofit Probe: Compatible Modernization for Legacy Vibration Monitoring Systems
The Bently Nevada 24701-28-05-00-026-04-02 is a high-precision eddy-current proximity probe assembly engineered for the 3300 XL Series continuous machinery protection platform. Designed as a retrofit-ready, drop-in replacement for aging or discontinued probe assemblies, this unit delivers full compatibility with existing 3300 XL monitor racks, extension cables, and Proximitor® sensor drivers without requiring hardware redesign or panel rewiring. Whether you are recovering a tripped machine train, upgrading a legacy vibration monitoring loop, or executing a planned outage replacement, the 24701-28-05-00-026-04-02 provides a verified, field-proven solution backed by a 12-month warranty and pre-shipment functional testing.
Industrial facilities running turbines, compressors, pumps, and gearboxes on Bently Nevada 3300 XL platforms frequently encounter the challenge of sourcing discontinued or long-lead probe assemblies. The 24701-28-05-00-026-04-02 addresses this directly: it maintains the original 8 mm probe tip diameter, standard 5-metre armored extension cable, and -24 VDC Proximitor® driver interface, ensuring that existing 3300 XL monitor cards — including the 3300/16 Dual Vibration Monitor and the 3300/20 Thrust Position Monitor — continue to operate within calibrated gap voltage ranges without reconfiguration. Technicians can retain original terminal block wiring on the 3300 XL I/O module and avoid costly re-engineering of the junction box layout.
For plants migrating from older Bently Nevada 7200 Series or 3000 Series probe systems to the 3300 XL architecture, the 24701-28-05-00-026-04-02 serves as the anchor component in a structured upgrade path. The migration typically involves replacing the legacy Proximitor® sensor with a 3300 XL-compatible driver, re-terminating the coaxial extension cable at the field junction box, and verifying the gap voltage at the 3300 XL monitor input using a calibrated gap simulator. During this process, engineers commonly work alongside the 3300/55 Keyphasor® Module to synchronize phase reference signals, and the 3300 XL Rack Power Supply to confirm that the additional probe load does not exceed the available current budget on the backplane.
Upgrade Compatibility Table
| Parameter | Original / Legacy | 24701-28-05-00-026-04-02 (3300 XL) |
|---|---|---|
| Probe Tip Diameter | 8 mm (standard) | 8 mm — direct fit, no adapter required |
| Extension Cable Length | 5 m armored coaxial | 5 m armored coaxial — same routing path |
| Proximitor® Driver Interface | -24 VDC, 3-wire | -24 VDC, 3-wire — retain existing terminal wiring |
| Gap Voltage Range | -10 VDC nominal at 1.0 mm | -10 VDC nominal at 1.0 mm — no recalibration needed |
| Monitor Card Compatibility | 3300/16, 3300/20, 3300/25 | Full compatibility confirmed |
| Communication Protocol | Hardwired analog 4–20 mA / voltage | Unchanged — no protocol migration required |
| Mounting Thread | M10 × 1.0 | M10 × 1.0 — same probe holder and bracket |
| Installation Requirement | Requires gap setting at commissioning | Gap set and verified pre-shipment |
| Warranty | Varies (OEM / aftermarket) | 12-Month Warranty — included |
| Retrofit Recommendation | — | Recommended for all 3300 XL platform upgrades |
Retrofit Planning for Existing Automation Systems
A successful retrofit using the 24701-28-05-00-026-04-02 begins well before the maintenance window opens. The first step is a full audit of the existing probe loop: confirm the Proximitor® sensor model installed in the field junction box, verify the extension cable condition and connector integrity, and document the current gap voltage reading from the 3300 XL monitor front panel. If the existing Proximitor® sensor is a legacy 3300 XL/05-02 or an older 7200 Series driver, it should be replaced concurrently with the probe to ensure the entire measurement chain is within specification.
During the outage, technicians typically work with the following components in the same control cabinet or rack: the 3300 XL Rack Power Supply (confirm available current margin before adding probe channels), the 3300/16 Dual Vibration Monitor card (verify channel assignment and alert/danger setpoints in the System 1 configuration database), and the 3300/55 Keyphasor® Module if phase-referenced measurements are required for balancing or orbit analysis. For plants that have integrated the 3300 XL platform with a DCS via the 3300 XL Data Manager or a Modbus gateway, the I/O mapping and tag assignments should be reviewed to confirm that the replacement probe channel retains the correct engineering unit scaling.
Where the control system includes a Bently Nevada 3500 Series rack operating in parallel — common in large turbine trains where the 3300 XL handles non-critical measurements and the 3500/42M Proximitor® I/O Module handles API 670-critical channels — the 24701-28-05-00-026-04-02 installation must be coordinated with the 3500 system’s bypass and inhibit logic to prevent spurious trips during the gap-setting procedure. The 3500 rack’s System 1 software should be placed in maintenance mode, and the relevant channel inhibited before the probe is disconnected.
For facilities using a Rockwell Automation ControlLogix or CompactLogix PLC to process the 4–20 mA analog output from the 3300 XL monitor, the analog input module — such as a 1756-IF16 or 1769-IF4 — should be verified for correct scaling after the probe replacement. If the plant uses a PROFIBUS DP or EtherNet/IP gateway to bridge the 3300 XL data to the PLC backplane, the gateway configuration file should be backed up before the outage and restored after commissioning to avoid tag mismatches. Programming cables and a laptop loaded with RSLogix 5000 or Studio 5000 should be on hand for any required ladder logic adjustments.
Downtime Control During System Migration
Minimizing unplanned downtime during a probe replacement on a running machine train requires a structured pre-outage checklist and a clear rollback plan. Before the maintenance window, download and archive the current System 1 configuration database, export the 3300 XL monitor card settings (alert/danger setpoints, time delays, relay logic), and photograph the existing terminal block wiring at the field junction box. This documentation ensures that if the replacement probe requires any gap adjustment, the original setpoints can be restored immediately without re-engineering.
During the outage, use a calibrated gap simulator to pre-set the 24701-28-05-00-026-04-02 to the nominal gap voltage before installation. This eliminates the need for iterative mechanical adjustment at the probe holder and reduces the time the machine train is offline. Once the probe is installed and the gap voltage confirmed at the 3300 XL monitor input, perform a channel-by-channel functional check: verify that the vibration reading is within the expected baseline range, confirm that the OK relay is energized, and check that the System 1 trend display shows a clean, noise-free signal. If the plant uses a Bently Nevada TDXnet or System 1 Evolution historian, verify that the new probe channel is logging data correctly before releasing the machine for restart.
For critical machinery where even a brief interruption to the protection system is unacceptable, consider a hot-swap approach using a spare 3300 XL monitor card pre-configured with the replacement probe’s calibration data. This allows the new probe to be commissioned on the spare card offline, with the card swap performed as a single, rapid operation during a brief process hold rather than a full shutdown.
Retrofit Support FAQ
Q1: Is the 24701-28-05-00-026-04-02 a direct replacement for the original Bently Nevada part, and will it work with my existing 3300 XL monitor cards?
Yes. The 24701-28-05-00-026-04-02 is manufactured to the original Bently Nevada dimensional and electrical specification. It is compatible with all 3300 XL Series monitor cards, including the 3300/16, 3300/20, and 3300/25, and uses the same -24 VDC Proximitor® driver interface and M10 × 1.0 probe thread. No hardware modifications to the monitor rack or field junction box are required.
Q2: What pre-shipment testing is performed, and what does the 12-month warranty cover?
Every 24701-28-05-00-026-04-02 unit undergoes a full functional test prior to shipment, including gap voltage verification at the nominal 1.0 mm gap, extension cable continuity check, and Proximitor® driver interface validation. The 12-month warranty covers manufacturing defects and functional failures under normal operating conditions. Units that fail within the warranty period are replaced or refunded at no additional cost.
Q3: Do I need to recalibrate the 3300 XL monitor after installing the replacement probe?
In most cases, no. Because the 24701-28-05-00-026-04-02 maintains the same sensitivity (200 mV/mil or 7.87 V/mm) and gap voltage characteristics as the original probe, the existing monitor card setpoints and scaling remain valid. However, it is good practice to verify the gap voltage at the monitor input after installation and compare it to the baseline recorded during the previous calibration. If the gap voltage deviates by more than ±0.5 VDC from the nominal value, a mechanical gap adjustment at the probe holder is recommended.
Q4: Can this probe be used in a system being migrated from a legacy Bently Nevada 7200 Series platform to the 3300 XL architecture?
Yes, with the appropriate Proximitor® sensor upgrade. The 24701-28-05-00-026-04-02 is designed for the 3300 XL Proximitor® driver interface and is not directly compatible with the 7200 Series driver without replacing the sensor. As part of a structured migration, the 7200 Series Proximitor® sensor should be replaced with a 3300 XL-compatible driver, after which the 24701-28-05-00-026-04-02 integrates seamlessly into the upgraded measurement loop. Our technical team can provide a migration checklist and wiring diagram upon request.
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