Epro PR9268/300-000 Velocity Sensor – PR9268 Series

Epro PR9268/300-000: Passive Electrodynamic Velocity Sensor for Continuous Machinery Protection

The Epro PR9268/300-000 is a passive, moving-coil electrodynamic velocity sensor engineered for permanent installation on rotating machinery in power generation, petrochemical, and heavy industrial environments. Unlike piezoelectric (IEPE/ICP) accelerometers that require a constant-current excitation supply, the PR9268/300-000 generates its output signal entirely from the relative motion between its internal permanent magnet and the surrounding coil winding — no external power source is required at the sensor head. This architecture makes it inherently fail-safe: a loss of supply voltage at the monitoring rack does not silence the sensor or produce a false “healthy” reading.

Within a machinery protection loop, the PR9268/300-000 occupies the first node in the signal chain. Its 300 mm integral cable terminates directly at the input barrier of compatible monitors such as the Epro CON021 or CON041, where the raw velocity signal is conditioned, integrated, and compared against alarm and trip thresholds. The sensor’s flat frequency response across 10–1,000 Hz covers the dominant vibration modes of most industrial rotating equipment — from low-speed cooling tower fans operating near 10 Hz to high-speed centrifugal compressors with blade-pass frequencies approaching 800–900 Hz.

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

Technical Parameters

Hardware Logical Analysis

The PR9268/300-000 is built around a spring-suspended permanent magnet assembly housed within a precision-wound copper coil. When the sensor body is bolted to a machine casing and the casing vibrates, the magnet — held stationary by its own inertia — moves relative to the coil. By Faraday’s law, this relative displacement induces an EMF proportional to the instantaneous velocity of the casing surface. The output is therefore a true velocity signal, not an integrated or differentiated approximation, which eliminates the phase error and noise amplification inherent in software-based integration of accelerometer data.

EMC and Shielding Architecture: The coil winding is enclosed in a ferromagnetic housing that acts as a Faraday shield, attenuating external magnetic field interference from motor stators, transformer leakage flux, and bus-bar proximity. The 2-wire cable is twisted-pair construction with an overall foil-and-braid shield, grounded at the monitor end only (single-point grounding) to prevent ground-loop currents from injecting 50/60 Hz common-mode noise into the differential input of the CON021/CON041 signal conditioner.

Mechanical Resonance Management: The spring-mass system of the moving magnet is tuned to a natural frequency well below 10 Hz — typically 4–6 Hz — ensuring that the sensor operates in its mass-controlled region across the entire 10–1,000 Hz measurement band. Within this region, the output amplitude is independent of frequency, producing the flat sensitivity curve (±3 dB) specified in the datasheet. The housing geometry and spring preload are matched to maintain this resonance point across the full −40 °C to +120 °C operating range, compensating for the thermal expansion coefficient of the spring steel.

IP67 Sealing Strategy: The cable entry point — historically the most common ingress failure mode in field-installed sensors — uses a dual-stage seal: a primary elastomeric gland compressed by the cable retention nut, backed by an internal epoxy potting compound that encapsulates the coil terminations. This arrangement maintains IP67 integrity even after repeated thermal cycling that would degrade a single-stage compression seal.

Passive Fail-Safe Logic: Because the sensor requires no excitation voltage, a broken wire or open-circuit fault at the cable produces a zero-volt output rather than a mid-scale or full-scale reading. Properly configured monitors (CON021 channel diagnostics) interpret a sustained zero-velocity reading on a running machine as a sensor fault condition and assert a “not OK” relay output — a deterministic, fail-safe response that prevents a damaged sensor from masking a genuine vibration alarm.

System Integration Benefits

• Zero-power sensor head: No excitation supply rail required at the sensor; simplifies intrinsic safety barrier design in Zone 1/Zone 2 hazardous areas and reduces the number of field wiring conductors from four (IEPE) to two.
• Direct monitor compatibility: Plug-and-play electrical interface with Epro CON021 and CON041 passive velocity inputs; no signal conditioner, charge amplifier, or impedance matching network is required between sensor and monitor.
• Deterministic real-time response: The analog signal path from sensor coil to monitor A/D converter introduces no digital latency. Alarm and trip relay response times are governed solely by the monitor’s hardware comparator, typically <1 ms — critical for turbine overspeed and compressor surge protection.
• Flat frequency response eliminates weighting filters: The 10–1,000 Hz ±3 dB band covers fundamental and second-harmonic running speed components for machines from 600 RPM to 30,000 RPM without requiring frequency-weighting correction curves in the monitor configuration.
• Dual-orientation mounting: Radial and axial installation on the same sensor body allows a single part number to cover both bearing-housing radial velocity and thrust-direction axial velocity measurement points, reducing spare-parts inventory complexity.
• Diagnostic transparency: Open-circuit and short-circuit faults produce unambiguous signal states (zero volts and near-zero impedance, respectively) that CON021/CON041 channel health monitoring can distinguish from normal low-vibration readings, enabling predictive maintenance teams to identify sensor degradation before a spurious trip occurs.
• Wide thermal operating envelope: The −40 °C to +120 °C rating covers outdoor installations in northern climates without heat tracing, as well as near-bearing installations on high-temperature steam turbines where surface temperatures routinely exceed 80 °C.
• IP67 ingress protection: Suitable for wash-down environments in food-grade compressor stations, offshore platform decks exposed to seawater spray, and underground pump stations subject to periodic flooding — without requiring additional weatherproof enclosures.

Quality Assurance & Global Logistics

Every Epro PR9268/300-000 unit dispatched from our Xiamen, China facility is sourced through verified supply channels and undergoes a structured pre-shipment inspection protocol. Physical integrity checks confirm that the sensor housing, cable jacket, and integral cable terminations show no mechanical damage, corrosion, or evidence of counterfeit labeling. Coil continuity and insulation resistance are verified against Epro factory acceptance criteria before packaging.

Units are shipped in anti-static, moisture-barrier packaging with desiccant inserts to prevent condensation damage during ocean freight transit. For urgent plant-shutdown requirements, DHL Express and FedEx International Priority services from Xiamen Gaoqi International Airport provide door-to-door delivery to major industrial hubs in Europe, Southeast Asia, the Middle East, and the Americas within 3–5 business days. All shipments include a commercial invoice, packing list, and certificate of origin to facilitate customs clearance. A 12-month warranty against manufacturing defects is provided on all units, with advance replacement available for qualified accounts to minimize plant downtime.

Contact Information

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