Overview
Configured for direct casing vibration measurement in machinery protection systems, the Emerson EPRO PR9268/301-100 (PR9268 electrodynamic velocity sensor) converts mechanical vibration into an analog AC voltage signal. Its self-powered moving-coil design requires no external excitation supply.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | PR9268/301-100 |
| Brand | Emerson / EPRO |
| Product Type | Electrodynamic Velocity Sensor / Absolute Vibration Sensor |
| Measurement Principle | Electrodynamic moving-coil, self-powered |
| Measurement | Absolute bearing housing and casing vibration |
| Mounting Orientation | Horizontal, +/- 10 deg deviation |
| Sensitivity | 28.5 mV/mm/s +/- 5% |
| Sensitivity, Imperial | 723.9 mV/in/s |
| Frequency Range | 4 to 1000 Hz |
| Natural Frequency | 4.5 Hz +/- 0.75 Hz at 20 deg C |
| Amplitude Linearity | < 2% |
| Maximum Acceleration | 10 g peak-peak continuous; 20 g intermittent |
| Transverse Acceleration | <= 2 g |
| Coil Electrical Resistance | 1875 ohm +/- 10% |
| Inductance | <= 90 mH, including cable |
| Capacitance | < 1.2 nF, including cable |
| Operating Temp | -20 deg C to +100 deg C |
| Relative Humidity | 0 to 100%, non-condensing |
| Protection Class | IP55 |
| Housing Material | Al-Mg-Si alloy |
| Cable | 5 m integrated PTFE cable with stainless steel armor |
| Cable Termination | Open ends |
| Power Consumption | None; self-powered measurement principle |
| Weight | Approx. 930 g, sensor body |
EPRO TSI Vibration Signal Characteristics
The PR9268/301-100 uses a moving-coil system to generate an electrical signal from mechanical casing motion. Therefore, the sensor does not require an external excitation voltage for measurement.
The output voltage varies with vibration velocity. Consequently, the connected monitoring channel can process the signal for casing vibration measurement and machinery protection functions.
The sensor covers 4 to 1000 Hz and has a nominal natural frequency of 4.5 Hz. This frequency response supports measurement of low-frequency mechanical vibration while maintaining a broad operating band.
The integrated 5 m armored PTFE cable provides the electrical connection between the sensor and the monitoring system. The stainless steel armor provides mechanical protection along the cable route.
Unlike powered process transmitters, this model does not operate as a 4-20 mA HART loop device. Instead, it provides the electrodynamic AC signal generated directly by the sensing element.
Frequently Asked Questions
Q: Does the PR9268/301-100 require an external power supply?
A: No. The sensor uses a self-powered moving-coil measurement principle and generates its output from mechanical vibration.
Q: What physical quantity does the sensor measure?
A: The sensor measures absolute bearing housing or casing vibration as vibration velocity.
Q: What cable configuration does this model provide?
A: The model includes a 5 m integrated PTFE cable with stainless steel armor and open-end termination.
Field Installation Guidelines
Install the sensor on a mechanically rigid measurement point that represents the bearing housing or casing vibration.
Maintain the specified horizontal mounting orientation and keep angular deviation within +/- 10 deg.
Route the armored cable away from strong mechanical movement, excessive heat, and sources of electrical interference. Avoid sharp bends or mechanical loading at the cable termination.
Connect the open cable ends according to the electrical requirements of the receiving machinery monitoring channel. Verify signal polarity and terminal identification before energizing or commissioning the monitoring circuit.
Provide a mechanically secure mounting interface so that the sensor follows casing motion without introducing avoidable structural movement.
Because the sensor has IP55 protection, verify that the installation environment does not expose the housing or cable termination to conditions beyond the specified protection level.
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