EPRO MMS3125022-020

Core Technical & Performance Parameters

• Measurement channel count: 2 independent eddy current probe input channels
• Compatible sensor: EPRO PR6423 / PR6424 series eddy current proximity probes with dedicated extension cables
• Probe gap measurement range: 0 ~ 2 mm standard calibrated range (model 022-020 factory preset)
• Measurement resolution: 0.1 μm; Full scale measurement accuracy: ±0.5% FS
• Signal processing metrics: Dynamic radial vibration peak-to-peak value, static DC average shaft gap position, probe gap voltage raw value
• Output signals per channel: Isolated 4–20 mA analog displacement output, buffered raw gap voltage BNC output
• Alarm relay outputs: Two programmable threshold relays (Alert / Trip) with configurable hysteresis and delay time to avoid transient false trips
• Sensor power supply: Internal built-in -24 VDC excitation power for eddy current probe coils
• Power supply to module: 24 VDC ±10% single power input, 3 W maximum power draw
• Operating temperature: 0°C ~ +70°C; Humidity tolerance 5% ~ 95% non-condensing
• Galvanic isolation: 2000 V isolation between probe input circuit and alarm relay output circuits
• Communication option: Rear RS485 Modbus RTU interface for remote shaft position data uploading to DCS systems

Function Features

1. Integrated cable length compensation circuit calibrated to 022-020 parameter code; automatically offsets signal attenuation from standard-length eddy current probe extension cables without external signal conditioning.
2. Simultaneous dual measurement capability: Each channel extracts static DC gap signal (average shaft position/thrust position) and AC dynamic vibration signal (radial shaft oscillation) from single probe input.
3. Built-in probe fault continuous diagnosis: Detect probe coil open circuit, cable short circuit, excessive probe-to-shaft gap out of measuring range, activate dedicated sensor fault relay alarm.
4. Configurable trip delay timer for machinery startup speed ramp phase; delays Trip alarm activation during transient speed fluctuations to eliminate false emergency shutdown.
5. Non-contact measurement principle eliminates mechanical wear between sensor and rotating shaft, long service life for continuous 24/7 turbomachinery operation.
6. Non-volatile EEPROM storage retains all threshold, delay and cable compensation parameters indefinitely without backup battery power.
7. Front panel BNC buffered raw gap voltage output connects portable oscilloscope for offline shaft orbit waveform analysis to diagnose rotor unbalance, misalignment and rub faults.
8. Potential-free heavy-duty trip relay contacts support direct connection to machine emergency shutdown safety logic circuits.

Material Composition & Structural Characteristics

• Module housing: Cold-rolled steel 19-inch rack pluggable subrack module, black powder coated front panel with status LED array.
• Analog measurement PCB: High-precision low-drift analog circuit board with conformal polyurethane coating resistant to turbine oil vapor and chemical atmosphere corrosion.
• Eddy current excitation circuit components: Low-temperature drift operational amplifiers and precision reference resistors calibrated during factory production for μm-level measurement stability.
• Rear terminal strip: Screw spring-clamp terminals for probe cable, power supply and alarm relay wiring, tin-plated contact pins anti-oxidation for long-term rack installation.
• Front panel interfaces: Dual BNC raw signal output connectors, power, channel status, alert and trip LED indicator lamps, module locking thumb screw.

Working Principle

Installation Requirements

1. Install into EPRO MMS3000 standard 19-inch rack subrack; tighten front panel locking screw to resist equipment floor vibration loosening module backplane connector.
2. Eddy current probe extension cables must be factory matched calibrated cables corresponding to model code 022-020; mismatched cable length leads to permanent measurement offset error unable to calibrate via software.
3. Probe signal cables must be fully shielded coaxial cable routed separate from high-voltage motor and excitation power cables with minimum 60cm clearance to prevent magnetic field interference distorting gap readings.
4. Alarm trip relay output wiring must use separate cable trunking isolated from low-level probe coaxial signal wiring to eliminate cross interference.
5. Rack cabinet must maintain constant temperature below 70°C; install cooling fan if ambient temperature fluctuates widely above 60°C.
6. All coaxial probe cable shielding must be grounded at module rear terminal only; double-point grounding creates circulating ground loop current causing measurement noise.

Application Scenarios

Operation & Maintenance Precautions

1. Re-calibrate probe gap measurement range every 12 months using standard calibration target block; long-term temperature cycling drifts analog circuit precision.
2. Never cut or splice eddy current probe extension cables in field; cable impedance mismatch invalidates factory length compensation calibration parameters permanently.
3. Front BNC raw signal output terminals cannot be short-circuited to cabinet ground; short circuit damages internal precision analog amplifier chips requiring full module replacement.
4. Continuous cabinet ambient temperature exceeding 70°C accelerates reference resistor drift, generating false Alert/Trip alarms during equipment normal running state.
5. Modbus RS485 bus terminal resistance jumper must be enabled at first and last module on bus segment; missing termination resistor causes unstable remote data communication.
6. Avoid mechanical shock impact during rack maintenance; internal low-drift analog components are highly sensitive to physical vibration and impact damage leading to permanent measurement deviation.