Emerson PR9268/017-100 | Electrodynamic Velocity Sensor – Vibration Monitoring Field Notes

• Description

Hard-Numbers: Technical Specifications

• Sensitivity: 28.5 mV/mm/s (±5% @ 80 Hz, 20°C, 100 Ω load)
• Frequency Range: 4 Hz to 1000 Hz (±3 dB)
• Natural Frequency: 4.5 Hz ±0.75 Hz @ 20°C
• Max Vibration Amplitude: 3000 µm p-p (4000 µm p-p optional)
• Max Acceleration: 10 g peak
• Operating Temperature: -20°C to +100°C (standard)
• Protection Class: IP67 (dust-tight, temporary immersion)
• Housing: Stainless steel, hermetically sealed
• Mounting: M10×1.5 stud, omnidirectional (any angle)
• Weight: 0.28 kg (0.62 lbs)
• Cable: 10 m standard, stainless steel armor, Harting connector
• Compliance: VDI 2059, API 670, CE, ATEX Zone 2

The Real-World Problem It Solves

Rotating machines lose balance, develop bearing wear, or loosen foundations—long before bearing temperature spikes. Contact probes wear out; eddy-current probes need power and target conductivity. This sensor delivers true absolute casing vibration with no external power, no target prep, and no direction lock.

Where you’ll typically find it:

• Steam/gas turbine casings (power plants, refineries)
• Centrifugal compressors (hydrocarbon, air separation)
• Large boiler fans, ID/FD fans, induced draft fans
• Critical pumps and gearboxes (high vibration, limited access)

Bottom line: It gives you early mechanical fault detection without the wiring and maintenance headaches of powered sensors.

Emerson PR9268/017-100​

Hardware Architecture & Under-the-Hood Logic

This is a passive electrodynamic pickup—no electronics, no power, just physics.

1. Sealed stainless housing holds a spring-mass-coil assembly.
2. Machine vibration moves the housing; the mass lags due to inertia.
3. Relative motion between coil and permanent magnet induces voltage proportional to velocity.
4. Output is a low-impedance AC voltage (28.5 mV per mm/s vibration velocity).
5. Omni-directional design means it responds equally in X/Y/Z axes—no careful alignment needed.
6. 4 Hz natural frequency ensures accurate measurement above ~10 Hz (typical machine fault frequencies).

Field Service Pitfalls: What Rookies Get Wrong

Mounting on Soft/Thin Brackets

Techs bolt it to thin, flexy brackets or loose casing lugs. Bracket resonance distorts readings—false high vibration, missed real faults.

• Field Rule: Mount directly to stiff, thick casing or solid foot; avoid brackets thinner than 6 mm. Torque M10 stud to 35–40 Nm.

Confusing with Eddy-Current Probes

Rookies wire it like PR642x eddy probes (24V power, 4–20 mA loop). This sensor is self-powered—applying 24V will burn the coil.

• Quick Fix: No supply voltage. Route twisted shielded pair to monitor input; shield ground at monitor end only.

Ignoring Cable Bend Radius & Chafing

Installers pull too tight, bend sharply (<50 mm radius), or run cable unprotected near hot pipes. Armor breaks, shield frays, intermittent noise.

• Field Rule: Min bend radius ≥50 mm; clamp cable every 0.5 m; keep clear of >120°C surfaces. Use metal conduit for high-chafe areas.

Commercial Availability & Pricing Note

Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability。