Siemens 6EW1890 Power Supply Modules – 6EW1890-3AA

Technical Dossier

Product Details And Specifications

Siemens 6EW1890 Series Technical Notes

The Siemens 6EW1890 series comprises regulated DC power supply modules engineered for continuous-duty operation within Siemens SIMATIC S5 and compatible rack-based control architectures. These units have accumulated substantial installed base across global heavy industry sectors including petrochemical refineries, nuclear auxiliary systems, offshore platform control rooms, and large-scale chemical processing facilities. Their role is foundational: they convert incoming AC mains voltage to stabilized DC bus power that feeds CPU, I/O, and communication modules within the same backplane. The 6EW1890 range was designed to meet the stringent uptime requirements of 24/7 continuous process environments where power interruption directly translates to production loss or safety risk. Units in this series are characterized by their DIN-rail or rack-mount form factor, short-circuit protection, overvoltage cutoff, and status LED diagnostics — all standard requirements for IEC 61131-compliant industrial control cabinets.

The Evolution of 6EW1890 Architecture

The 6EW1890 series was introduced as part of Siemens' SIMATIC S5 power infrastructure ecosystem during the late 1980s and early 1990s. At that time, the dominant industrial control paradigm relied on centralized rack systems where a single power supply module served multiple I/O and CPU cards via a shared backplane bus. The 6EW1890 was designed to fulfill this role with a fixed DC output (typically 24 VDC or 5 VDC depending on variant), current ratings matched to the aggregate load of a fully populated S5 rack, and passive cooling suitable for enclosed cabinet installation.

Q: How are RFQ terms confirmed?
A: Quantity, required condition, documentation needs, destination and sourcing route are confirmed during RFQ review before quotation.

6EW1890 Full Catalog & Functionalities (SKU List)

The following SKUs represent the documented variants within the Siemens 6EW1890 power supply module family, classified by output specification and application context:

Power Supply Modules — Primary DC Output Variants

• 6EW1890-3AA: 24 VDC regulated output power supply module for SIMATIC S5 rack; standard current rating for mid-density I/O configurations.
• 6EW1890-3AB: 24 VDC output variant with extended current capacity; suited for fully populated S5 racks with high analog I/O density.
• 6EW1890-3AC: 24 VDC output with enhanced EMC filtering; specified for installations adjacent to high-frequency drive equipment.
• 6EW1890-3BA: 5 VDC logic bus supply variant; provides internal logic rail power for CPU and digital I/O modules in S5 central racks.
• 6EW1890-3BB: 5 VDC output with increased current rating; used in CPU-intensive configurations with multiple co-processor modules.
• 6EW1890-3CA: Dual-output variant (5 VDC + 24 VDC); consolidates logic and field power into a single module slot for space-constrained enclosures.
• 6EW1890-3CB: Dual-output high-current variant; supports mixed digital/analog rack configurations with elevated total power demand.
• 6EW1890-3DA: Wide-range AC input (85–264 VAC) power supply; designed for installations with unstable mains or international voltage compatibility requirements.
• 6EW1890-3DB: Wide-range input with extended hold-up time; maintains output during mains interruptions up to 20 ms for ride-through capability.
• 6EW1890-3EA: Redundancy-capable module; supports parallel operation with load-sharing for high-availability control architectures.
• 6EW1890-3EB: Redundancy module with active current balancing; used in 1+1 redundant PSU configurations in critical process control panels.
• 6EW1890-3FA: 48 VDC output variant; specified for telecom-adjacent control systems and relay logic panels requiring 48 V field power.
• 6EW1890-3FB: 48 VDC high-current output; supports solenoid valve banks and actuator arrays in process automation skids.
• 6EW1890-3GA: 24 VDC output with integrated diagnostics relay; provides dry-contact fault output for integration with plant-wide alarm management systems.
• 6EW1890-3HA: Low-profile form factor variant; designed for compact S5 sub-racks and distributed I/O enclosures with restricted vertical clearance.

Sourcing Hard-to-Find & Obsolete 6EW1890 Parts

For facilities operating under long-term service agreements (LTSA) or multi-year maintenance contracts, DriveKNMS can provide framework supply arrangements that guarantee availability of specific 6EW1890 variants over defined contract periods. This eliminates the risk of emergency sourcing delays during unplanned outages.

Quality Control for the 6EW1890 Range

Power supply modules present specific test challenges compared to I/O or communication modules. The 6EW1890 series requires validation across both electrical output parameters and internal protection circuit functionality. DriveKNMS applies the following test protocol to all 6EW1890 units processed through its facility:

• Input voltage sweep test: Unit is energized across the full specified AC input range to verify regulation performance at voltage extremes.
• Output voltage accuracy: DC output is measured under no-load, 50% load, and full-rated load conditions using calibrated bench instruments. Tolerance must be within ±1% of nominal.
• Ripple and noise measurement: Output ripple is measured at full load using an oscilloscope. Excessive ripple indicates capacitor degradation — a common failure mode in aged units.
• Overcurrent protection test: Load is incrementally increased beyond rated current to verify that the overcurrent protection circuit activates within specified parameters without latching fault.
• Thermal stress cycle: Unit is operated at full load for a minimum of 2 hours with ambient temperature monitoring to identify thermal derating or intermittent component failures.
• Backplane connector inspection: Edge connector pins are inspected under magnification for oxidation, mechanical deformation, or solder joint fatigue — the primary cause of intermittent rack communication faults.
• Isolation resistance test: Input-to-output and input-to-chassis isolation resistance is verified to confirm that internal insulation has not degraded due to moisture ingress or thermal aging.