EPRO PR9268/302-000 Velocity Sensor – PR9268 Series

EPRO PR9268/302-000 — Seismic Velocity Transducer for Industrial Machinery Protection Systems

In rotating machinery protection, the velocity transducer occupies a structurally critical position in the measurement chain. Unlike proximity probes that measure shaft displacement relative to a bearing housing, or accelerometers that output high-frequency acceleration data requiring double integration, the electrodynamic velocity sensor delivers a self-generated, broadband velocity signal directly proportional to the absolute vibration velocity of the machine casing. The EPRO PR9268/302-000 is a precision electrodynamic seismic velocity sensor from the PR9268 Series, engineered for continuous deployment in turbomachinery protection loops, compressor monitoring systems, and heavy-duty rotating equipment installations where measurement integrity and long-term mechanical stability are mandatory requirements.

EPRO, now operating within the Baker Hughes Bently Nevada portfolio, has produced the PR9268 Series to IEC and ISO machinery monitoring standards. The PR9268/302-000 variant is specified for bearing housing mounting and is widely integrated into OEM protection architectures across power generation, oil & gas processing, and petrochemical refining sectors. Its passive electrodynamic operating principle — requiring no external excitation voltage for the sensing element — makes it inherently suitable for SIL-rated safety instrumented systems where power supply failure modes must be minimized.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The PR9268/302-000 operates on the moving-coil electromagnetic induction principle. Internally, a permanent magnet assembly is mechanically coupled to the sensor housing via a calibrated spring-mass suspension system. A precision-wound coil is suspended within the magnetic field gap. When the housing undergoes vibration, the inertia of the magnet assembly causes relative motion between the coil and the magnetic field, inducing a voltage proportional to the instantaneous velocity of the housing surface — directly implementing Faraday’s law of electromagnetic induction without any active electronic components in the signal path.

Spring-Mass Resonance Engineering: The internal suspension is tuned to a resonant frequency well below the machine’s fundamental operating frequency (typically 1× running speed). For a 3,000 RPM machine (50 Hz), the sensor resonance at ~10 Hz ensures the measurement band from 10 Hz to 1,000 Hz operates in the flat, calibrated region of the frequency response curve. The mechanical Q-factor of the suspension is damped using viscous fluid or eddy-current damping to prevent resonance amplification from distorting the output signal.

EMC Design Architecture: The passive output stage eliminates the common-mode noise injection risks associated with active sensor electronics. The stainless steel housing provides a Faraday shield effect, attenuating capacitively coupled interference from adjacent high-voltage cabling. The coil winding is configured in a differential topology where the output terminals present a balanced impedance to the signal conditioning input, enabling common-mode rejection ratios (CMRR) exceeding 60 dB in typical industrial cable runs up to 100 m.

Mechanical Durability Under Continuous Vibration: The spring-mass suspension is designed for continuous operation at vibration amplitudes up to the sensor’s rated measurement range without fatigue failure. The coil former material and winding adhesive are selected for thermal stability across the full operating temperature range, preventing sensitivity drift caused by thermal expansion mismatch between the coil and former.

Self-Generating Signal Integrity: Because the PR9268/302-000 generates its own output voltage through electromagnetic induction, it remains functional during power supply interruptions to the monitoring system — a critical characteristic for SIL 2 and SIL 3 safety loops where sensor availability during power transients must be maintained. The output impedance is low enough to drive standard 4–20 mA transmitter inputs or direct monitor card inputs without signal loading errors.

System Integration Benefits

• Direct monitor card compatibility: The PR9268/302-000 output is electrically compatible with EPRO MMS 6000 velocity input cards and Bently Nevada 3500/42M velocity monitor modules, requiring no signal conditioning intermediary and eliminating one potential failure point in the measurement chain.
• No power supply dependency in the sensing element: The passive electrodynamic design means the sensor continues to generate a valid velocity signal even if the monitor rack power supply experiences a momentary dropout, preserving alarm and trip function continuity during power transients.
• Broadband frequency coverage: The flat response from approximately 2 Hz to 1,000 Hz captures both low-frequency structural resonances (sub-synchronous instabilities, oil whirl at 0.4–0.5×) and higher-frequency bearing defect frequencies (BPFO, BPFI) within a single measurement channel, reducing the number of transducers required per measurement plane.
• Deterministic alarm response: The analog velocity output feeds directly into the monitor’s comparator circuit with no digital conversion latency in the sensor itself, ensuring that trip signals are generated within the monitor’s specified response time — typically <100 ms for overspeed or high-vibration events.
• Diagnostic transparency via trend data: Continuous velocity amplitude trending in the DCS historian enables detection of gradual bearing wear, rotor imbalance progression, and misalignment development weeks before alarm thresholds are reached, supporting condition-based maintenance scheduling.
• Stud-mount mechanical interface: The rigid stud-mount connection to the bearing housing ensures that the sensor housing faithfully tracks the housing vibration without the resonance artifacts introduced by magnetic base or adhesive mounting methods, maintaining measurement traceability to ISO 10816 and ISO 20816 standards.
• Cable run flexibility: The low output impedance and balanced coil topology allow signal cable runs up to 100–200 m without significant signal attenuation or noise pickup, enabling remote monitor rack placement in control rooms away from high-temperature or high-vibration zones.
• Cross-compatibility with legacy EPRO systems: The PR9268/302-000 maintains electrical and mechanical backward compatibility with earlier EPRO velocity sensor generations, allowing direct replacement in existing installations without rewiring or monitor reconfiguration, minimizing maintenance downtime.

Quality Assurance & Global Logistics

Every PR9268/302-000 unit supplied by siemensplc.com is sourced through verified industrial supply channels with documented traceability. Each unit undergoes incoming inspection against OEM reference standards, including visual examination of housing integrity, connector condition, cable jacket continuity, and label authenticity verification. Units supplied as new carry original EPRO/Baker Hughes packaging with manufacturer batch documentation where available.

Our warehouse is located in Xiamen, China — a major international logistics hub with direct air freight connections to Frankfurt, Amsterdam, Dubai, Singapore, Houston, and Los Angeles. Standard in-stock orders are processed and dispatched within 1–3 business days. International shipments are handled via DHL Express, FedEx International Priority, or UPS Worldwide Expedited, with full export documentation including commercial invoice, packing list, and certificate of origin. For time-critical plant shutdowns or emergency maintenance windows, same-day dispatch arrangements are available upon request.

All supplied components carry a 12-month warranty from the date of shipment, covering manufacturing defects and premature failure under normal operating conditions. Warranty claims are processed with a target response time of 48 hours, and replacement units are dispatched from stock where available to minimize plant downtime impact.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.