EPRO PR6424/010-040 CON021 Proximity Sensor – PR6424 Series

EPRO PR6424/010-040 CON021 — Eddy Current Proximity Probe Assembly for Shaft Displacement Monitoring

The EPRO PR6424/010-040 CON021 is a non-contact eddy current proximity probe assembly engineered for continuous radial shaft displacement and vibration measurement in critical rotating machinery. The PR6424 series operates on the principle of electromagnetic induction: a high-frequency oscillator drives a coil wound at the probe tip, generating an alternating magnetic field. When a conductive target surface enters this field, eddy currents are induced, loading the oscillator circuit and producing a voltage output proportional to the gap distance between probe face and target. This linear, non-contact transduction mechanism eliminates mechanical wear entirely, making the PR6424/010-040 CON021 assembly suitable for continuous 24/7 operation in turbomachinery protection systems where sensor longevity and signal fidelity are non-negotiable.

The /010-040 suffix designates a 1.0 m probe cable with a 4.0 m extension cable via the CON021 connector interface, yielding a total system cable length of 5.0 m from probe tip to driver input. This cable length configuration is selected to match the characteristic impedance requirements of the PR6424 driver electronics, ensuring the oscillator operates within its calibrated frequency window and maintains the specified sensitivity of −8 mV/µm (−200 mV/mil) across the full linear measurement range.

Designed for direct integration with EPRO PR9268 and PR9270 series driver/monitor modules, the PR6424/010-040 CON021 is also fully signal-compatible with Bently Nevada 3300 XL and 3500 series proximity monitor cards, making it a verified drop-in replacement in existing machinery protection architectures without requiring recalibration of the monitor system.

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

Technical Parameters

Hardware Logical Analysis

The PR6424 probe tip houses a precision-wound ferrite-core coil encapsulated in a thermally stable ceramic-filled epoxy compound. This encapsulation serves a dual function: it mechanically protects the coil geometry against vibration-induced deformation (which would shift the probe’s characteristic curve) and provides electrical isolation between the coil and the stainless steel probe housing, preventing ground loop interference from the machinery frame.

Oscillator Loading and Sensitivity Linearity: The eddy current driver (PR9268/PR9270) maintains the probe coil at a fixed oscillation frequency, typically in the range of 1.0–1.5 MHz for the PR6424 series. As the target gap decreases, eddy current losses increase, reducing the effective Q-factor of the tank circuit. The driver’s automatic gain control (AGC) loop compensates for this loading by adjusting drive amplitude, and the resulting AGC correction voltage is output as the gap-proportional DC signal. This architecture produces a highly linear transfer function across the specified 0.25–2.25 mm range, with non-linearity typically held to ±0.5% of full scale.

EMC Design: The coaxial cable construction of both the probe cable and the CON021 extension provides continuous shielding from probe tip to driver input. The shield is grounded at the driver end only (single-point grounding), eliminating shield current loops that would otherwise inject 50/60 Hz power-line noise into the measurement signal. The CON021 connector body is machined from stainless steel with a gold-plated center contact, maintaining shield continuity and minimizing contact resistance variation over the connector’s service life.

Thermal Stability: EPRO specifies the PR6424 sensitivity coefficient at 25°C against AISI 4140 steel. Over the operating temperature range of −35°C to +120°C, the sensitivity drift is controlled to within ±0.05 mV/µm/°C through the selection of low-temperature-coefficient coil wire and the ceramic-filled encapsulant, which has a thermal expansion coefficient matched to the ferrite core. This thermal management is critical in steam turbine bearing housings where probe body temperatures can reach 80–100°C during normal operation.

Cable Impedance Matching: The /010-040 cable length combination (1.0 m probe + 4.0 m extension = 5.0 m total) is not arbitrary. EPRO calibrates each PR6424 driver to a specific cable capacitance range. Deviating from the specified cable length alters the tank circuit capacitance, shifting the oscillator frequency and displacing the sensitivity curve. The CON021 extension cable uses a defined coaxial geometry (characteristic impedance 50 Ω) to ensure the total cable assembly presents the correct capacitive load to the driver, preserving factory calibration without field adjustment.

System Integration Benefits

• 1. Direct Bently Nevada 3300/3500 Compatibility: The PR6424/010-040 CON021 output signal (−2 VDC to −18 VDC at −8 mV/µm) is electrically identical to Bently Nevada 7200 and 3300 XL series probe outputs. Monitor cards require no sensitivity rescaling or jumper changes, enabling direct replacement in existing machinery protection panels.
• 2. DC-to-10 kHz Flat Frequency Response: The probe assembly captures both quasi-static shaft position (DC component, indicating bearing wear or thermal bow) and dynamic vibration up to 10,000 Hz (600,000 RPM equivalent), covering all subsynchronous, synchronous, and supersynchronous vibration components in a single measurement channel.
• 3. Zero Mechanical Wear: Non-contact measurement eliminates probe-to-shaft contact, removing the failure mode of probe tip erosion present in contact-type displacement sensors. Mean time between replacement is determined by cable fatigue and connector wear, not by the sensing element itself.
• 4. IP67 Ingress Protection: The probe body and CON021 connector are rated IP67, providing complete protection against oil mist, cooling water spray, and condensation in bearing housings and gearbox environments without requiring additional protective enclosures.
• 5. Single-Cable Signal and Power: The coaxial cable carries both the −24 VDC supply from the driver and the output signal on the same conductor pair, simplifying field wiring. No separate power cable is required at the probe location, reducing installation complexity in congested machinery skids.
• 6. Deterministic Analog Output: The DC voltage output is inherently deterministic — there is no digital protocol latency, no fieldbus arbitration delay, and no firmware-dependent scan cycle. Signal propagation from gap change to driver output is governed by the AGC loop bandwidth, typically settling within 100 µs, making the PR6424 suitable for machinery protection systems requiring sub-millisecond trip response.
• 7. Broad DCS Platform Compatibility: The −2 to −18 VDC output is accepted directly by EPRO PR9268/PR9270 drivers, which in turn provide 4–20 mA or ±10 V outputs for integration with ABB System 800xA, Emerson DeltaV, Honeywell Experion PKS, and Siemens PCS 7 / PCS neo DCS platforms without signal conditioning adapters.
• 8. Functional Safety System Integration: When paired with EPRO MMS6000 or Bently Nevada 3500 series monitors, the PR6424 measurement chain can be incorporated into SIL 2 machinery protection loops per IEC 61511. The analog signal path has no firmware, eliminating software-related common-cause failure modes in the sensor layer of the safety instrumented function.
• 9. Modular Cable Length Selection: The PR6424 series is available in multiple probe and extension cable length combinations. The /010-040 variant covers installations where the driver cabinet is located up to 5.0 m from the bearing housing. Longer runs (up to 9.0 m total) are achievable with the /010-080 or /010-090 variants using the same CON021 interface, allowing standardization of connector inventory across a plant.
• 10. Minimal Installation Footprint: The 8 mm probe tip diameter allows installation in compact bearing housings where larger 11 mm or 25 mm probes cannot be accommodated. The M10 × 1.0 thread (standard for PR6424) is compatible with existing probe holders designed for Bently Nevada 7200 series probes of equivalent tip diameter.

Quality Assurance & Global Logistics

Every EPRO PR6424/010-040 CON021 unit dispatched from our Xiamen, China facility is sourced through documented industrial supply channels and undergoes a structured pre-shipment inspection protocol. Physical inspection covers probe housing integrity, cable jacket condition, CON021 connector pin alignment and gold-plating condition, and label marking verification against EPRO factory part number conventions. Functional verification confirms oscillator operation by checking driver output voltage at a known reference gap using a calibrated test fixture. Units that do not meet EPRO factory specification tolerances are quarantined and not offered for sale.

A 12-month warranty is provided from the date of shipment, covering manufacturing defects and premature failure under normal operating conditions. Certificate of Conformance (CoC) documentation is available upon request for all dispatched units.

Logistics from Xiamen, China: In-stock units are dispatched within 1–3 business days via DHL Express, FedEx International Priority, or UPS Worldwide Expedited. Export documentation — including commercial invoice, packing list, and HS code 9031.80 declaration — is prepared for each shipment. FORM E (ASEAN preferential origin) is available for eligible destinations. Bulk orders of 5 or more units qualify for consolidated sea freight via Xiamen Port, one of China’s primary export hubs, with direct services to major industrial ports in Europe, Southeast Asia, the Middle East, and the Americas. Lead time for special-order or non-stock configurations is 7–15 business days.

Contact Information

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