EPRO PR6424/000-000 CON21 Proximity Sensor – PR6424 Series

EPRO PR6424/000-000 CON21 — 8 mm Eddy Current Proximity Sensor for Rotating Machinery Protection

The PR6424/000-000 CON21 is an 8 mm eddy current proximity sensor manufactured by EPRO GmbH, a Baker Hughes company, and is a core measurement element in API 670-compliant machinery protection systems. It operates on the principle of electromagnetic induction: a high-frequency oscillating magnetic field generated at the sensor tip induces eddy currents in any proximate conductive target. The resulting impedance change in the sensor coil is processed by a paired signal conditioner — typically the EPRO CON021 series — to produce a calibrated DC voltage output proportional to the gap distance between sensor tip and target surface.

Unlike contact-based displacement transducers, this non-contact architecture eliminates mechanical wear, making the PR6424/000-000 CON21 suitable for continuous, uninterrupted monitoring of shaft radial vibration, axial position, and differential expansion in steam turbines, gas turbines, centrifugal compressors, and large rotating machinery operating under API 670 protection standards. The CON21 suffix designates the integral connector style, which mates directly with the PR9268 extension cable assembly without field-wiring termination, reducing installation error and maintaining signal integrity across the full cable run.

This unit is stocked and dispatched from Xiamen, China, with full traceability documentation. For pricing and lead time, contact [email protected] or WhatsApp +86 18359268345.

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

Technical Parameters

Hardware Logical Analysis

The PR6424/000-000 CON21 employs a two-wire coaxial architecture in which the sensor coil, housed within a threaded stainless-steel body, forms one arm of an LC oscillator circuit completed inside the CON021 conditioner. At the nominal operating frequency of approximately 1 MHz, the coil radiates a focused electromagnetic field with a depth of penetration governed by the skin effect equation δ = √(2ρ / ωμ), where ρ is target resistivity, ω is angular frequency, and μ is magnetic permeability. For AISI 4140 steel at 1 MHz, the effective penetration depth is approximately 8–12 µm, confining the eddy current loop to the target surface and making the measurement insensitive to subsurface metallurgical variation.

The CON21 integral connector eliminates the impedance discontinuity that arises when field-terminated connectors introduce parasitic capacitance at the junction. The coaxial cable run between sensor and conditioner is treated as a transmission line; EPRO specifies matched cable impedance (typically 50 Ω) and maximum cable length to maintain oscillator stability and prevent standing-wave distortion of the output signal. This design discipline is critical in high-vibration environments where cable flexure could otherwise modulate the signal baseline.

EMC performance is achieved through the coaxial shielding of the entire signal path and the differential input architecture of the CON021 conditioner, which rejects common-mode noise induced by adjacent power cables, variable-frequency drives, and high-current bus bars — all typical in turbomachinery enclosures. The sensor body’s stainless-steel housing provides additional electrostatic shielding and mechanical protection against hydraulic oil, steam condensate, and process gas ingress, consistent with its IP67 rating.

Temperature compensation is embedded in the conditioner’s analog signal chain. The CON021 applies a polynomial correction derived from the sensor’s factory characterization data, maintaining output linearity within ±0.5% of full scale across the full –40 °C to +120 °C tip temperature range. This eliminates the need for field recalibration when ambient conditions shift during seasonal operation or process load changes.

System Integration Benefits

• Deterministic gap-to-voltage linearity: Factory sensitivity of 7.87 V/mm (±0.1% tolerance) allows direct engineering-unit scaling in DCS historian tags without per-unit calibration offsets, reducing commissioning time on multi-shaft installations.
• Zero mechanical wear: Non-contact measurement eliminates bearing load from the sensing element, enabling continuous 24/7 monitoring without scheduled sensor replacement intervals — a direct reduction in planned maintenance downtime.
• API 670 alarm and trip integration: Output voltage range (typically –2 V to –18 V DC) maps directly to the input card specifications of Bently Nevada 3500 and EPRO MMS 6000 racks, enabling plug-and-play alarm setpoint configuration without signal conditioning adapters.
• Dual-plane vibration measurement: Two PR6424/000-000 CON21 sensors mounted at 90° on a single bearing journal provide X-Y orbit plot data, enabling shaft centerline analysis and early detection of rotor instability, oil whirl, and misalignment.
• Axial position monitoring: When paired with a thrust collar target, the sensor resolves axial displacement to ±2.5 µm resolution, providing the primary input for thrust bearing wear alarms in API 670 protection logic.
• DCS 4–20 mA loop compatibility: Via the CON021 conditioner’s optional current output module, the sensor integrates into ABB, Siemens, Honeywell, and Yokogawa DCS analog input cards without additional signal converters, preserving loop isolation and ground integrity.
• Diagnostic transparency: The conditioner’s OK relay output provides a hardware-level sensor health signal — open on loss of oscillation or cable fault — that can be wired directly to the DCS discrete input for automated sensor fault alarming without software polling.
• High-temperature process compatibility: The –40 °C to +120 °C tip rating covers the majority of steam turbine bearing housing environments without requiring the higher-cost PR6426 high-temperature variant, optimizing bill-of-materials cost on standard installations.

Quality Assurance & Global Logistics

Every PR6424/000-000 CON21 unit dispatched from our Xiamen warehouse is sourced exclusively from EPRO-authorized distribution channels or directly from Baker Hughes-certified supply chains. Each unit carries a traceable serial number that can be cross-referenced against EPRO’s factory production records. Pre-shipment inspection covers visual integrity of the sensor tip and body, dimensional verification of the CON21 connector, and electrical continuity of the coil circuit. Calibration certificates are available upon request at no additional charge for in-stock units.

Shelf-life management is enforced: no units with storage periods exceeding manufacturer recommendations are dispatched without explicit disclosure and buyer consent. Export compliance review — including ECCN classification and destination control — is completed for all international orders prior to shipment release.

Logistics from Xiamen, China, are executed via DHL Express, FedEx International Priority, and UCP freight for volume orders. Standard in-stock orders ship within 2–3 business days. Full commercial invoice, packing list, and certificate of origin documentation are provided for customs clearance. Warranty coverage is 12 months from the date of shipment, covering manufacturing defects under normal operating conditions.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.