Description
Emerson EPRO PR6424/003-030 | Eddy Current Probe System
Architect’s Product Breakdown
The PR6424/003-030 + CON021 is a non-contact shaft measurement assembly used in rotating machinery monitoring. Its eddy current probe detects changes in the gap between the probe tip and a conductive shaft, while the CON021 signal converter conditions the measurement for use by compatible machinery monitoring equipment. Applications include radial shaft vibration, axial displacement, shaft position, eccentricity, and speed/key measurement.
The PR6424 family has a nominal sensitivity of 4 V/mm on the specified standard steel target, with a standard static measuring range of ±2.0 mm. The standard PR6424 converter configuration is associated with a 4.0 mm total measuring range. Do not confuse this with extended-range configurations, which require the appropriate converter variant and different sensitivity scaling.
For a legacy installation, verify the complete probe designation, cable assembly, converter model, monitor input range, and mechanical installation gap before approving a replacement. The PR6424/003-030 + CON021 designation alone is not sufficient evidence that every unit sold under that description has the same cable configuration or calibration. For trip-critical machinery, confirm the installed measurement chain against the original equipment documentation.
PR6424/003-030+CON021
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Probe model | PR6424/003-030 |
| Converter model | CON021 |
| Measurement principle | Eddy current, non-contact |
| Sensor family | |
| Nominal sensitivity | 4 V/mm on specified standard target material |
| Standard static measuring range | ±2.0 mm |
| Standard total measuring range | 4.0 mm |
| Standard-range linearity error | ≤ ±1.5% |
| Converter frequency response | 0–20 kHz at −3 dB |
| Converter rise time | Less than 15 µs |
| Converter supply voltage | −23 to −32 VDC for the −4 to −20 V output configuration |
| Alternative converter output configuration | −2 to −18 VDC, with supply of −21 to −32 VDC |
| Converter operating temperature | −30°C to +100°C |
| Converter protection rating | IP20 |
| Transducer connector | Self-locking LEMO connector on the CON021 |
The sensitivity and measuring range above refer to the standard PR6424 configuration. Extended-range applications require a separately specified converter. Confirm the exact probe construction, cable length, and connector from the unit’s nameplate and applicable datasheet.
Field Engineer’s Pitfall Guide
Warning 1 — Standard and extended measuring ranges are not interchangeable.
The standard PR6424 configuration uses a 4.0 mm total measuring range. Extended-range versions require the matching converter designation and different sensitivity. A mismatch can produce incorrect vibration amplitudes or shaft displacement readings even when the system produces an apparently stable output.
Warning 2 — Set the probe gap using the specified calibration procedure.
The installation gap determines the operating point within the converter’s output range. An incorrect gap can push the measurement toward the edge of its linear region, reducing usable travel in one direction. Establish the gap using the manufacturer’s procedure and verify the resulting output before connecting the channel to active protection logic.
Warning 3 — Do not assume the receiving monitor uses the correct scaling.
The CON021 provides a voltage output, not a generic 4–20 mA transmitter signal. Check the receiving monitor’s input type, polarity, scaling, and alarm thresholds. Incorrect scaling can make a healthy probe appear faulty or, more seriously, make excessive shaft movement appear acceptable.
QA & Testing SOP
- Visual and origin inspection: Verify OEM markings, model and serial labels, connector condition, cable jacket, probe tip, and signs of previous installation or repair.
- Electrical checks: Confirm converter supply polarity, operating voltage, terminal condition, and output configuration.
- Live functional test: Test the PR6424 probe with its compatible CON021 converter using a suitable calibrated target and fixture.
- Measurement verification: Check output response across the specified measuring range, sensitivity, linearity, and signal stability.
- Documentation: Record model and serial numbers, test results, calibration information where available, and the as-tested configuration. Firmware recording is not normally applicable to this analog sensor assembly.
- Packaging: Protect the probe tip and connector, secure the cable against sharp bends, and use appropriate antistatic and mechanical protection.
Acceptance rule: A powered-up converter is not proof of a calibrated measurement chain. Require documented functional testing before installing the assembly in a machinery protection application.
Technical FAQ
Q1. Can I replace a PR6424/003-030 assembly with another PR6424 probe?
Only after checking the full part number, mechanical dimensions, cable assembly, calibration, and converter range. Sharing the PR6424 family designation does not establish complete interchangeability.
Q2. Does the CON021 need firmware flashing?
No routine firmware flashing is required for this analog signal converter. The important checks are probe compatibility, converter measuring range, power supply, and analog output configuration.
Q3. Can I replace the probe while the machine is running?
Do not assume that online replacement is permitted. Disturbing a probe can interrupt a machinery protection channel. Follow the site’s approved maintenance, isolation, and bypass procedures, including any required compensating protection.
Q4. Will the measurement configuration be retained after a power failure?
The probe and CON021 are analog hardware; they do not retain a PLC application program. Monitoring thresholds, channel scaling, and trip logic reside in the receiving monitoring system. Verify those settings and the restored signal after power returns.
Q5. Does new-surplus stock include an OEM warranty?
Not automatically. New-surplus condition and warranty coverage are separate matters. Obtain written confirmation of condition, functional test status, warranty provider, warranty period, and return terms before purchase.
