BENTLY 3500/50 286566-02 | 3500/50M Tachometer Module

• Brand: Bently Nevada
• Full Model Number: 3500/50 286566-02
• Lifecycle Status: Current 3500/50M family
• Core Function: Two-channel Tachometer Module
• Top 3 Technical Specs: 2 channels; 1–50,000 rpm speed range; proximity-probe or magnetic-pickup inputs
• System: Bently Nevada 3500 Machinery Protection System
• Module Type: 3500/50M Tachometer Module
• Measurements: Shaft speed; rotor acceleration/deceleration; rotor direction
• Alarm Functions: Speed setpoint; speed band; zero-speed; acceleration; reverse-rotation alarming
• Keyphasor Function: Conditioned Keyphasor signal to 3500 rack backplane
• Peak Hold: Highest speed; highest reverse speed; reverse-rotation count
• Configuration: 3500 Rack Configuration Software
• Stock & Condition: Exact stock confirmation required; New Surplus / Tested Refurbished; Emergency shipping subject to cutoff

Baker Hughes identifies 286566-02 as the Bently Nevada 3500/50M Tachometer Module. It is a two-channel module accepting proximity-probe or magnetic-pickup signals for shaft speed, rotor acceleration, and rotor direction. The module can also provide conditioned Keyphasor signals to the 3500 rack backplane.

Module 3: Obsolescence & Supply Chain Deep Dive

A failed 3500/50M 286566-02 can remove shaft-speed and rotational-status information used for speed alarms, zero-speed detection, acceleration monitoring, and reverse-rotation notification. The module has two independent input channels and supports programmable monitoring functions through the 3500 Rack Configuration software. It can also distribute conditioned Keyphasor signals through the rack backplane, eliminating the need for a separate Keyphasor module when that function is enabled.

From a TCO standpoint, replacing the exact tachometer module preserves the existing 3500 rack, speed sensors, alarm logic, and downstream monitoring architecture. That is materially less costly than redesigning a complete machinery-protection installation around a different speed-monitoring platform. Procurement should still distinguish this module from the dedicated 3500/53 Overspeed Detection System: Baker Hughes states that the 3500/50M provides tachometer monitoring functions, while its separate overspeed product is intended for dedicated overspeed protection. (For a shutdown-critical machine, that functional distinction should be documented before PO approval.)

Module 4: Compatibility & Replacement Matrix

The manufacturer datasheet states that the 3500/50M is programmed with 3500 Rack Configuration software and supports speed setpoint, speed-band, zero-speed, acceleration, and reverse-rotation monitoring modes.

⚠️ Field Traps — Watch Out

• Tachometer vs Overspeed Protection: Do not specify the 3500/50M as a substitute for a dedicated 3500/53 overspeed protection system without an engineering review. Baker Hughes separately identifies an Overspeed Protection System as a distinct product.
• Sensor Type and Channel Mapping: Each channel can receive a proximity-probe or magnetic-pickup signal. Record the existing sensor type, channel assignment, scaling, and alarm settings before replacing the module.

BENTLY 3500/50 286566-02

Module 5: Quality Assurance & Testing SOP

1. OEM anti-counterfeit visual inspection — verify Bently Nevada identification, 286566-02 marking, front-panel labels, connectors, status indicators, and manufacturing traceability.
2. Hardware revision audit — record all visible revision markings and compare them with the installed module.
3. Mechanical inspection — examine card guides, ejector hardware, connectors, buffered-transducer interfaces, and PCB edges for damage or deformation.
4. PCB condition inspection — check for corrosion, contamination, overheated components, cracked solder joints, damaged traces, and unauthorized modification.
5. Electrical pre-screening — verify continuity, grounding, isolation, and sensor-input integrity before energization.
6. Power-on self-test (POST) — install the module in an approved 3500 test rack and verify normal initialization and diagnostic status.
7. Sensor-input simulation — independently apply representative proximity-probe and magnetic-pickup signals to both input channels.
8. Speed calculation test — apply known pulse frequencies and verify the indicated shaft speed across representative low, midrange, and high-speed points.
9. Acceleration/deceleration test — apply controlled frequency ramps and verify rotor acceleration/deceleration calculations.
10. Zero-speed test — remove the simulated rotational input and verify the configured zero-speed notification or alarm behavior.
11. Reverse-rotation test — simulate reverse-direction conditions where configured and verify the expected status/alarm response.
12. Speed alarm test — simulate configured Alert/Danger or other speed setpoints and verify correct alarm behavior.
13. Peak-hold test — verify highest-speed, highest-reverse-speed, and reverse-rotation-count storage and reset functions as configured.
14. Keyphasor backplane test — verify conditioned Keyphasor signal availability to the 3500 rack backplane where enabled.
15. Status LED verification — confirm expected OK, TX/RX, and BYPASS behavior during controlled operating conditions.
16. Extended energized run — monitor speed stability, diagnostics, signal continuity, and unexpected module resets.
17. Final QC release — retain channel-by-channel test records, identification photographs, configuration data, ESD-safe packaging records, and full traceability.

For this module, a basic powered-on test is insufficient. The meaningful acceptance sequence is pulse detection, speed calculation, alarm behavior, directional detection, peak-hold operation, and rack-level Keyphasor verification.

Module 6: Procurement & Lifecycle FAQ

Q1. Is BENTLY 3500/50 286566-02 genuinely in stock, and what is the cutoff for emergency shipping?
Exact availability should be confirmed against 3500/50M 286566-02, quantity, condition, and destination before PO release. Current supplier listings show limited and surplus inventory for this part, so emergency dispatch should be based on confirmed physical stock rather than catalog availability.

Q2. How do you verify the condition and authenticity of an obsolete or surplus 286566-02?
Require OEM marking inspection, complete part-number verification, PCB and connector examination, electrical screening, powered 3500-rack testing, two-channel pulse simulation, speed verification, alarm testing, direction testing, peak-hold verification, and Keyphasor backplane testing. The unit should remain traceable to its QC record.

Q3. Are there firmware or configuration issues engineers should check before issuing the PO?
Yes. The 3500/50M is programmed through 3500 Rack Configuration software, so engineers should preserve the existing speed range, alarm setpoints, monitoring mode, sensor type, channel assignments, and Keyphasor configuration before replacement.

Q4. Can 3500/50M 286566-02 replace a 3500/50 133388-02?
Do not assume direct interchangeability from the common 3500/50 family designation. 286566-02 is the 3500/50M tachometer module, while older 3500/50 hardware uses different part numbering and may have different hardware/configuration requirements. Match the complete installed configuration before substitution.

Q5. What warranty and return terms should procurement require?
Require a written warranty period, DOA criteria, return-authorization procedure, serial/part-number traceability, and exclusions for incorrect sensor wiring, configuration errors, electrical overstress, or installation damage. The quotation should explicitly state 3500/50M 286566-02, tested condition, and revision information.