Epro PR6423/001-121 Eddy Current Probe Sensor

Product Overview

The Emerson EPRO PR6423/001-121 is a high-precision 8 mm eddy-current proximity probe developed for continuous monitoring of rotating machinery dynamics. It is designed to measure shaft displacement-related parameters including vibration, axial movement, eccentric position, and rotational instability.

The probe is typically deployed in conjunction with EPRO signal conditioning units such as CON021 or CON041, forming a complete displacement measurement chain used in API 670-aligned protection and monitoring systems.

Its compact probe geometry, high thermal endurance, and rugged construction make it suitable for demanding turbomachinery environments.

Measurement Principle

This sensor operates using eddy-current induction technology. Variations in the gap between the probe tip and conductive shaft surface generate proportional electrical signals, which are processed by a compatible converter to derive precise displacement values.

The system is optimized for both static and dynamic measurement tasks in high-speed rotating equipment.

Technical Specifications

Sensing Performance

• Measurement principle: Eddy-current non-contact displacement sensing

• Probe diameter: 8 mm

• Linear measuring range: 2.0 mm (80 mil)

• Nominal air gap: 0.5 mm

• Sensitivity: 8 V/mm (±5%)

• Linearity deviation: ±0.025 mm full scale

• Frequency response: DC to 10 kHz

• Minimum shaft diameter: ≥25 mm

• Target material: Magnetic steel (e.g., AISI 4140 / 42CrMo4 equivalent)

Mechanical Construction

• Thread type: M10 × 1 or 3/8”-24 UNF

• Sensor body: Stainless steel housing

• Sensing tip: High-performance PEEK polymer

• Connector material: Nickel-plated brass

• Cable insulation: PTFE high-temperature resistant jacket

• Standard cable diameter: 2.8 mm

• Armored cable option: ~6 mm

Environmental Performance

• Operating temperature (probe): –35 °C to +180 °C

• Cable/connector temperature limit: up to +150 °C

• Protection rating: IP66 (dust-tight, jet-water resistant)

• Shock resistance: up to 40 g mechanical load

• Minimum bend radius: 25 mm (standard cable), 35 mm (armored version)

Signal Characteristics

• Output signal type: Raw eddy-current analog signal (requires CON021/CON041 conditioner)

• Stable performance across wide thermal gradients

• High immunity to electromagnetic interference in industrial environments

• Optimized for long-term drift stability in continuous monitoring systems

System Integration Notes

The PR6423/001-121 is not a standalone transmitter. It requires a compatible EPRO signal converter for calibration, linearization, and standard output generation (4–20 mA or voltage output).

Typical matched systems include:

• CON021 signal conditioner

• CON041 advanced processing module

This pairing ensures factory-aligned calibration and eliminates field adjustment requirements.

Industrial Applications

• Steam and gas turbine shaft vibration monitoring

• Centrifugal and axial compressor displacement tracking

• Pump rotor eccentricity detection

• Gearbox shaft alignment and thermal expansion analysis

• High-speed rotating machinery condition monitoring

FAQ

Q: Does PR6423/001-121 provide direct 4–20 mA output?
A: No. It outputs a raw eddy-current signal and requires a CON-series signal conditioner.

Q: Is this sensor suitable for high-temperature turbines?
A: Yes. The probe supports continuous operation up to +180 °C.

Q: Can it be used for vibration measurement?
A: Yes. It is widely used for shaft vibration and displacement-based condition monitoring.

Q: What makes this model different from larger probes?
A: The 8 mm design allows installation in compact bearing housings while maintaining high sensitivity.