Emerson EPRO CON021/916-240 + PR6426/010-140 Eddy Current Displacement System

The Emerson EPRO CON021/916-240 + PR6426/010-140, also cataloged as the CON021+PR6426 displacement system, operates as a dedicated hardware component for high-precision shaft dynamics measurement within industrial condition monitoring networks. This matched probe and signal conditioning converter assembly tracks radial vibration and axial position against large-diameter rotating targets, providing high-bandwidth analog output for machinery protection logic.

Hardware Specifications

Bently Nevada / VIBRO-METER Technical Characteristics

• Eddy-Current Probe Scaling: The PR6426 series utilizes specialized coil winding geometry to achieve a 2 V/mm sensitivity over an extended 24 mm range. The CON021/916-240 converter scales these impedance variations into a standardized negative-going output signal, maintaining the required precision for large-shaft turbomachinery monitoring.
• Gap Voltage Validation: Successful integration requires validation of the nominal air gap (approx. 5.5 mm). The converter output must be calibrated to the factory-defined negative voltage target at this nominal gap to ensure the system operates within the linear portion of its 24 mm extended range.
• Rotor Dynamics and Signal Processing: The assembly supports a bandwidth up to 20,000 Hz, allowing for the detection of high-frequency vibration signatures. This high-speed response is essential for monitoring large-diameter shafts (>= 200 mm) where rotational speeds and surface velocities (up to 2,500 m/s) require high-fidelity signal tracking.

Frequently Asked Questions

Q: Is the system compatible with standard 24 VDC positive-ground power supplies?

A: No. The CON021/916-240 requires a negative DC power rail (-21 V to -32 V). This is a legacy requirement for API 670 compliant protection racks. Applying positive voltage to the supply input will prevent the oscillator circuit from initializing and may cause internal protection diode activation.

Q: How does the shaft diameter affect system performance?

A: This sensor is optimized for shaft diameters >= 200 mm. The large sensing face of the PR6426/010-140 is designed to integrate the flux across a wide surface. Using this probe on small-diameter shafts will cause the electromagnetic field lines to wrap around the shaft geometry, causing significant sensitivity errors and non-linear output response.

Field Installation Guidelines

• Mounting and Alignment: Secure the probe into the bearing casing using the threaded stainless steel sleeve. Establish the 5.5 mm nominal air gap using a non-magnetic feeler gauge. Because this system is intended for high-speed machinery, ensure the probe locknuts are torqued to prevent mechanical backing-out caused by machine casing thermal expansion.
• Shielding and Grounding: Terminate the coaxial LEMO connector securely. Route the PTFE-insulated cable through rigid, grounded metallic conduit to suppress high-frequency electromagnetic interference. The cable shield must be terminated at the monitoring rack's instrumentation earth bus only; ensure no conductive path exists between the probe housing and the instrumentation ground at the machine casing to avoid the formation of parasitic ground loops.