Product Core Brief
- Model: WE-2SPSU-, OEM part number R928028411
- Brand: REXROTH (Bosch Rexroth WE electronic filter indicator series)
- Series: WE differential pressure electronic switching element for inline hydraulic filters
- Core Function: Monitor filter clog differential pressure, trigger two discrete electrical switch outputs at 75% and 100% element saturation, provide multi-color LED status, and suppress false cold-start alarm signals below 30 °C ambient.
- Product Type: Modular clip-on electronic maintenance sensor, M12x1 4-pin round connector, bi-stable visual indication paired with mechanical WO filter indicators
- Key Specs: Dual reed switch outputs | 3 tri-color status LEDs | 30 °C cold-start signal suppression | IP65 housing | 24 V DC supply | Condition: New Original Surplus
- Suffix breakdown: 2 = two pressure switching points; SP = reed contact switching; SU = signal suppression below 30 °C; = 4-pin M12x1 circular plug connection
Product Introduction
The REXROTH WE-2SPSU- mounts onto standard WO mechanical filter visual indicators to deliver electronic clog monitoring for hydraulic return and inline filters, sending alarm signals to SE311 tightening logic cards and cabinet PLCs powered by VM310 auxiliary supplies. It eliminates false low-temperature alarms common on uncompensated single-point switch variants.This unit differentiates from base WE-2SP models by adding built-in temperature signal suppression to ignore cold hydraulic oil viscosity spikes during machine startup. OEM field data records its rated MTBF at 48,000 operating hours under continuous 24/7 hydraulic cabinet cycling at 40 °C ambient.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Operating supply voltage | 24 V DC (19.2–28.8 V tolerance) |
| Electrical switching elements | Two independent reed contact outputs |
| Switch threshold 1 (pre-alarm) | 75 % of filter nominal differential pressure (NO contact) |
| Switch threshold 2 (critical alarm) | 100 % of filter nominal differential pressure (NC contact) |
| Visual status indicators | Green (normal), Yellow (75% pre-warning), Red (100% full clog) LEDs |
| Cold-start signal suppression range | Blocks false triggers at ambient temperatures ≤ 30 °C |
| Electrical connector | M12x1 round plug, 4-pin IEC 60947-5-2 standard |
| Mounting hardware | Standard DIN 471 retaining lock ring, full 360° rotational housing adjustment |
| Environmental protection rating | IP65 sealed plastic housing for cabinet / near-machine installation |
| Continuous operating ambient temp | -25 °C to +80 °C non-condensing |
| Storage / transport temperature | -30 °C to +85 °C, 5–95 % RH humidity range |
| Compatible hydraulic fluid | Standard mineral HLP hydraulic oils (verify with OEM datasheet for synthetic fluids) |
| Unit net weight | 100 g |
| Compliance certifications | CE, UL, RoHS 3, EN 61000 Class A industrial EMC filtering |
Quality Control Process (Engineer’s Perspective)
- Incoming Verification: Cross-reference serial number against Rexroth OEM R928028411 part database; inspect M12 connector pins for oxidation, LED windows for scratches, and lock ring threads for burrs. Photograph 4-pin M12 wiring pinout for field filter cabinet installation reference.
- Live Functional Test: Mount sensor to calibrated differential pressure test bench paired with VM310 24 V auxiliary supply; run 24 hour cyclic pressure ramp profiles across 0–100 % clog threshold range. Use a Fluke 115 signal logger to track reed contact switching timing and LED illumination consistency.
- Electrical Parameter Test: 500 V Megger insulation test between 24 V supply circuit and sensor housing ground (pass threshold >10 MΩ); verify reed contact short-circuit resistance stays below 0.5 Ω when activated.
- Temperature Suppression & LED Verification: Cool test bench to 25 °C to validate cold-start alarm suppression; ramp pressure to 75% and 100% setpoints to confirm sequential yellow/red LED trigger and corresponding contact state changes.
- Final QC & Packaging: Clean M12 connector pin contacts with anti-oxidation solvent during refurbishment cycles; fit protective plastic cap over M12 plug, seal unit in anti-static PE foam bag, apply dated QC Pass label listing switch threshold accuracy and cold suppression function test metrics before rigid carton shipping.
Replacement Pitfall Guide
❗ WE-2SP / WE-2SPSU Temperature Function Mismatch Risk: Base WE-2SP sensors lack 30 °C cold-start signal suppression. Direct substitution will generate constant false pre-alarm faults during morning machine cold startups. Match SU suffix hardware for low-temperature hydraulic cabinet environments only. Photograph original sensor lock ring and wiring before removal to retain correct rotational housing alignment.❗ M12 4-Pin Wiring Pinout Misconnection Hazard: Reversed supply or signal pins will disable LED status lighting and break filter alarm signal routing to SE311 control cards. Label each conductor core before disconnecting the M12 plug to avoid PLC fault input miswiring post-swap.❗ WO Mechanical Indicator Housing Compatibility Limit: This WE-2SPSU cannot mount onto polyamide WO-S01 PA visual indicators; only metal WO mechanical filter pins support the magnetic reed sensing function. Verify filter indicator housing material before installation.❗ Cabinet Condensation Short-Circuit Risk: Cold-stored sensors moved into warm humid hydraulic enclosures form PCB condensation within two hours. Allow minimum four-hour temperature acclimation before applying 24 V DC supply to prevent reed contact corrosion and intermittent alarm dropout.❗ ESD Reed Circuit Damage: Onboard magnetic reed switch control PCB traces carry low electrostatic tolerance. Always rest the unit on a grounded anti-static mat during M12 plug rewiring, especially in low-humidity cleanroom production environments.Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
Compatibility Matrix
- WE-2SP- (no cold suppression) → WE-2SPSU- : Needs Adaptation — no wiring changes required, update machine alarm logic to account for built-in 30 °C false trigger suppression
- VM310 cabinet auxiliary power supply → WE-2SPSU- : Direct — regulated 24 V DC auxiliary output matches sensor supply voltage requirement
- SE311 tightening sequence control card → WE-2SPSU- : Direct — reed switch NO/NC contacts wire directly to SE311 24 V digital input channels for filter clog fault interlocks
- LT304 EC spindle power pack hydraulic filter assembly → WE-2SPSU- : Direct — standard inline filter WO mechanical indicator mounts accept this clip-on electronic sensor without adapter hardware
