EPRO PR6423/13R-030 CON021 Eddy Current Sensor – PR6423 Series

EPRO PR6423/13R-030 CON021 — Non-Contact Eddy Current Probe for Rotating Machinery Protection

The PR6423/13R-030 CON021 is a 13 mm-tip eddy current proximity probe manufactured by EPRO GmbH (a Baker Hughes / Bently Nevada ecosystem-compatible brand) and designed for continuous, non-contact measurement of radial shaft vibration and axial position displacement in critical rotating machinery. The probe operates on the inductive eddy current principle: a high-frequency oscillator (typically 1 MHz carrier) drives a coil wound at the probe tip, generating an alternating electromagnetic field. When a conductive target — typically an AISI 4140 steel journal — enters this field, eddy currents are induced on the target surface, loading the oscillator circuit. The resulting change in oscillator amplitude is demodulated by the paired CON021 driver into a DC voltage proportional to the air gap between probe face and shaft surface. This voltage signal is then conditioned by an EPRO MMS 6000 or MMS 3000 series monitor card for alarm, trip, and data acquisition functions.

The 13 mm tip diameter is the standard API 670 probe boss dimension for medium-frame turbomachinery. It fits bearing housing probe ports on most OEM steam turbines, centrifugal compressors, and turbo-expanders without requiring machined adapter bushings. The 3.0 m integral cable (suffix -030) eliminates one field-junction point in the measurement chain, reducing the risk of ground loops and connector-induced signal noise in high-EMI machine rooms. The CON021 connector mates directly with EPRO extension cables (5 m, 9 m) and MMS 6000 input cards, maintaining a fully matched, factory-calibrated signal chain.

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Technical Parameters

Hardware Logical Analysis

The PR6423/13R-030 CON021 measurement chain is built around a Colpitts-type LC oscillator embedded in the probe body. The coil inductance shifts as a function of target proximity, and this shift is translated into a proportional DC output by the CON021 driver’s demodulation stage. Several hardware design decisions distinguish this probe from lower-grade alternatives:

• Differential coil winding geometry: The 13 mm tip uses a balanced coil arrangement that partially cancels common-mode electromagnetic interference. In machine rooms where variable-frequency drives and high-current bus bars generate broadband EMI (typically 150 kHz – 30 MHz), this geometry maintains signal integrity without requiring additional shielding conduit.
• Integral cable construction: The 3.0 m cable is a coaxial assembly with a low-loss polyethylene dielectric and a double-braid shield. The shield is terminated at the CON021 connector with a 360° circumferential crimp, not a pigtail, which suppresses high-frequency shield resonance that would otherwise appear as noise on the –24 VDC signal line.
• Probe body material and thermal compensation: The probe housing is machined from 316L stainless steel, which provides corrosion resistance in oil-mist environments and a low coefficient of thermal expansion. The coil former material is selected to minimize inductance drift across the –35 °C to +120 °C operating range, keeping scale factor variation within ±1% across the full thermal envelope — a critical requirement for axial position measurement where a 10 µm drift can trigger a false thrust bearing alarm.
• CON021 connector sealing: The connector body incorporates a dual O-ring face seal rated IP67. In bearing housing installations where oil splash and steam condensate are present, this prevents moisture ingress that would shift the coil’s dielectric constant and alter the calibration curve.
• Factory calibration traceability: Each PR6423/13R-030 unit is calibrated against an AISI 4140 target on a precision linear stage with 1 µm resolution. The calibration data is stored with the unit serial number, enabling field verification of scale factor without removing the probe from its mounting boss.

System Integration Benefits

• 1. Direct API 670 compliance: The 13 mm tip and CON021 connector conform to API 670 (5th Edition) dimensional and electrical requirements, allowing the probe to be installed in any API 670-compliant probe boss without modification. This eliminates the engineering review cycle required when substituting non-standard sensors.
• 2. Matched signal chain with MMS 6000 monitors: When paired with EPRO MMS 6110 (vibration) or MMS 6120 (position) input cards, the PR6423/13R-030 CON021 operates as a factory-matched system. The monitor’s internal gain and offset registers are pre-configured for the 8 mV/µm scale factor, so no field calibration adjustment is required at commissioning.
• 3. Bently Nevada 3300/3500 cross-compatibility: With appropriate driver selection, the PR6423 series output voltage range (–2 V to –18 V) is compatible with Bently Nevada 3300 XL and 3500 series monitor input specifications. This allows mixed-fleet installations to standardize on a single probe model across different monitor platforms.
• 4. Zero mechanical wear — continuous duty: Non-contact measurement eliminates probe-to-shaft contact wear. The sensor is rated for continuous 24/7 operation across the full temperature range, with no scheduled replacement interval based on mechanical degradation — only periodic calibration verification per API 670 maintenance schedules.
• 5. DC to 10 kHz frequency response: The flat frequency response from DC (static gap) to 10,000 Hz covers all rotating machinery vibration frequencies of interest, including sub-synchronous instability (oil whirl at 0.4–0.5× running speed), synchronous 1× unbalance, and high-order harmonics from gear mesh or blade passing on multi-stage compressors running at speeds up to 30,000 RPM.
• 6. Deterministic analog output for DCS integration: The –2 V to –18 V DC output is a low-impedance analog signal that interfaces directly with standard 4–20 mA transmitter input cards via a simple V-to-I converter, or directly with high-impedance analog input modules on Siemens S7-400H, ABB System 800xA, or Emerson DeltaV DCS platforms without signal conditioning.
• 7. Diagnostic transparency via gap voltage monitoring: The raw gap voltage (accessible at the CON021 driver output) provides a continuous, real-time diagnostic channel. Operators can trend the static gap voltage to detect slow shaft centerline migration caused by bearing wear, thermal growth, or foundation settlement — conditions that are invisible to vibration-only monitoring systems.
• 8. Reduced installation risk with integral cable: The 3.0 m integral cable eliminates the probe-to-extension-cable junction inside the bearing housing, which is the highest-risk connection point for moisture ingress and mechanical damage. Fewer field connections mean fewer potential failure modes in the measurement chain and lower maintenance labor during outage inspections.

Quality Assurance & Global Logistics

All EPRO PR6423/13R-030 CON021 units supplied by siemensplc.com are sourced through verified industrial distribution channels and subject to a structured incoming inspection protocol before dispatch:

• Visual inspection of probe tip, cable jacket, and CON021 connector body against OEM dimensional drawings
• Continuity and insulation resistance measurement on the integral coaxial cable (minimum 100 MΩ at 500 VDC)
• CON021 connector mating test with a reference extension cable to verify contact engagement and O-ring seating
• Serial number verification against EPRO production records where available
• ESD-safe packaging in anti-static foam with desiccant, sealed in a moisture-barrier bag prior to shipment

Shipments originate from our warehouse in Xiamen, China. Standard export routes cover Europe (DHL Express, 3–5 business days), North America (FedEx International Priority, 4–6 business days), Southeast Asia (2–3 business days), and the Middle East / Africa (5–8 business days). Full export documentation is provided as standard: commercial invoice, packing list, certificate of origin, and HS code 9031.80 classification. ATEX/IECEx documentation and third-party inspection certificates (SGS, Bureau Veritas) can be arranged on request for projects requiring import compliance in regulated markets.

All units carry a 12-month warranty from the date of shipment against manufacturing defects. Warranty claims are processed with a target response time of 2 business days. Replacement units are dispatched from Xiamen stock on the next available export flight.

Contact Information

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