EPRO PR6423/015-000-CN CON021 Proximity Sensor – MMS 6000 Series

EPRO PR6423/015-000-CN CON021 — Eddy Current Proximity Transducer for Rotating Machinery Condition Monitoring

The EPRO PR6423/015-000-CN CON021 is a non-contact eddy current proximity transducer engineered for continuous shaft vibration, axial position, and differential expansion measurement in critical rotating machinery. Operating on the principle of electromagnetic induction, the sensor generates a high-frequency oscillating magnetic field at its tip. When a conductive target enters this field, eddy currents are induced on the target surface, loading the oscillator circuit and producing a DC output voltage proportional to the gap distance between probe tip and target. This analog output — nominally 8 mV/µm — feeds directly into EPRO MMS 6000 or MMS 6350 signal conditioning modules without requiring field calibration, provided the target material matches the factory calibration standard (AISI 4140 steel).

The /015 suffix designates a 1.5-metre integral cable, which determines the total electrical length of the probe-cable system. This length is a fixed parameter in the oscillator tuning: substituting a cable of different length will shift the sensitivity curve and introduce measurement error. The CON021 connector assembly provides the standardized EPRO bayonet interface, ensuring mechanical and electrical continuity between the probe body and the extension cable or driver input. The connector’s gold-plated contacts maintain contact resistance below 10 mΩ across the rated temperature range, preventing signal degradation in high-vibration environments.

In turbomachinery protection systems, the PR6423/015-000-CN CON021 is typically deployed in pairs at each radial bearing plane, oriented 90° apart (X–Y configuration), to resolve the full orbital trajectory of the shaft. A third probe may be added at the thrust bearing for axial position monitoring. The sensor’s 0–15 mm linear measurement range accommodates standard API 670 gap settings of 1.0–1.5 mm at mid-range, providing symmetric dynamic headroom for both inward and outward shaft excursions. At the nominal 1.27 mm (50 mil) gap, the output sits at approximately −10.2 VDC, consistent with EPRO and Bently Nevada driver input conventions.

The probe body is machined from 316L stainless steel with a PEEK (polyether ether ketone) tip encapsulant. PEEK’s dielectric constant of 3.2 and its thermal stability to 250 °C ensure that the electromagnetic field geometry remains stable across the full operating temperature range of −40 °C to +120 °C. The M14 × 1.5 thread allows direct installation into standard API 670-compliant proximity probe holders without adapter sleeves. IP67 ingress protection is achieved through a dual-seal arrangement at the cable entry point, rated for 30-minute immersion at 1-metre depth — adequate for steam turbine bearing housings subject to condensate accumulation.

siemensplc.com maintains verified stock of the PR6423/015-000-CN CON021 sourced through traceable supply channels. Each unit is inspected against EPRO factory documentation prior to dispatch. All shipments originate from Xiamen, China, with DHL Express and FedEx International Priority options available for next-flight-out requirements.

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

Technical Parameters

Hardware Logical Analysis

The PR6423 series employs a Colpitts-type LC oscillator embedded in the probe tip, operating at a carrier frequency of approximately 1 MHz. This frequency is selected to balance penetration depth into the target material (skin depth δ ≈ 50 µm in AISI 4140 at 1 MHz) against sensitivity to surface geometry variations. The oscillator’s tank circuit is formed by the probe coil inductance and two series capacitors, making the resonant frequency — and therefore the output voltage — a deterministic function of the coil-to-target gap. Because the oscillator is physically located at the probe tip rather than in a remote driver box, the system avoids the cable-length sensitivity errors inherent in driver-remote architectures; however, this also means the integral cable length is a calibration parameter and cannot be field-modified.

EMC performance is achieved through a triaxial cable construction: the signal conductor is surrounded by an inner shield (driven at signal potential to eliminate cable capacitance loading) and an outer shield connected to chassis ground. This guard-driven topology reduces the effective cable capacitance seen by the oscillator from several hundred picofarads to below 5 pF per metre, preserving oscillator Q-factor and sensitivity linearity across the full 1.5 m cable run. The CON021 connector’s shell provides 360° RF shielding continuity at the mating interface, preventing common-mode noise ingress at the highest-impedance point in the signal chain.

Thermal drift compensation is implemented through a matched NTC thermistor network embedded in the probe body adjacent to the coil. The thermistor’s resistance-temperature characteristic is selected to counteract the positive temperature coefficient of the coil inductance, maintaining sensitivity within ±0.5% across the −40 °C to +120 °C operating range without external correction. This passive compensation approach eliminates the need for temperature lookup tables in the signal conditioner firmware, reducing system latency and simplifying SIL 2 functional safety validation.

System Integration Benefits

• Direct MMS 6000 / MMS 6350 compatibility: The PR6423/015-000-CN CON021 is factory-matched to EPRO’s MMS 6000 series vibration monitoring modules. No sensitivity scaling or offset adjustment is required at commissioning, reducing startup time by eliminating the gap-voltage verification loop typically needed with third-party probes.
• API 670 5th Edition compliance: The probe meets all dimensional, electrical, and documentation requirements of API 670, enabling direct use in machinery protection systems for compressors, turbines, and pumps subject to API standards without additional qualification testing.
• Deterministic analog output: The DC voltage output (nominally −24 VDC to 0 VDC across the measurement range) is inherently latency-free. There is no digital conversion, fieldbus encoding, or protocol stack between the physical gap and the monitor input — critical for protection systems requiring sub-millisecond response to shaft excursions.
• Plug-compatible with CON041 armored extension: Where the 1.5 m integral cable is insufficient, the CON021 connector mates directly with EPRO CON041 armored extension cables in standard lengths (3 m, 5 m, 9 m), extending reach without affecting the calibrated sensitivity, provided the total system cable length remains within the driver’s specified range.
• Dual-plane orbital analysis support: Deploying two PR6423 probes at 90° at each bearing plane provides the X and Y displacement signals required for full orbital trajectory reconstruction in EPRO MMS 6000 or third-party vibration analysis software, enabling detection of sub-synchronous instability, oil whirl, and rub events.
• Keyphasor phase reference integration: The PR6423 series is approved for use as a speed/phase reference (Keyphasor) probe when targeting a shaft notch or keyway, providing the once-per-revolution trigger signal required for synchronous vibration analysis and balancing operations.
• SIL 2 functional safety pathway: The passive, fail-safe analog output architecture — where cable open-circuit drives the output to the negative rail and short-circuit drives it to zero — provides inherent diagnostic coverage for wiring faults without additional hardware. This behavior is consistent with SIL 2 loop design requirements under IEC 61508 when combined with a suitable safety-rated monitor.
• Minimal DCS integration overhead: The ±24 VDC-powered, voltage-output interface is natively accepted by all major DCS analog input cards (4–20 mA conversion via EPRO MMS 6350 or direct high-impedance voltage input on Siemens SIMATIC, ABB 800xA, Emerson DeltaV, and Honeywell Experion platforms) without signal conditioning adapters.

Quality Assurance & Global Logistics

Every PR6423/015-000-CN CON021 unit supplied by siemensplc.com is sourced through verified channels with full traceability to EPRO GmbH manufacturing records. Pre-shipment inspection includes: visual examination of probe tip, cable jacket, and connector shell for mechanical damage; continuity and insulation resistance measurement (≥ 100 MΩ at 500 VDC between signal conductor and shield); and output voltage verification at a calibrated 1.27 mm gap against a reference AISI 4140 target block. Units that do not meet the ±2% output tolerance at the nominal gap are quarantined and returned.

Original EPRO factory packaging — including the foam-lined transit case, calibration data sheet, and material certificate — is preserved intact. Calibration certificates traceable to national standards are available on request for units requiring documented metrological traceability. Anti-counterfeit verification is performed by cross-referencing the probe serial number against EPRO’s part marking conventions and inspecting the holographic authenticity label on the connector assembly.

Logistics operations are based in Xiamen, China (Fujian Free Trade Zone), providing direct access to Xiamen Gaoqi International Airport (XMN) and Xiamen Port for both air and sea freight. Standard dispatch is DHL Express Worldwide with transit times of 3–5 business days to Europe and North America, 2–3 days to Southeast Asia. FedEx International Priority and TNT Economy Express are available as alternatives. For shutdown-critical requirements, same-day airport drop-off is available for orders confirmed before 14:00 CST. Export documentation — including commercial invoice, packing list, certificate of origin, and CN customs declaration — is prepared in-house, with HS code 9031.80.90 applied for eddy current proximity transducers.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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