Siemens 6EP1436-3BA00 Industrial Power Supply – SITOP PSU300S

Siemens 6EP1436-3BA00 SITOP PSU300S 40A — Three-Phase Stabilized Power Supply for High-Demand Industrial Control Systems

The 6EP1436-3BA00 is a three-phase stabilized DC power supply within Siemens’ SITOP PSU300S product family, rated at 40 A continuous output at 24 VDC. Its primary function in a control architecture is to serve as the centralized DC bus source for distributed I/O racks, PLC backplanes, field instrumentation loops, and safety relay chains. Unlike single-phase SITOP variants, the PSU300S draws from a balanced 3-phase 400–500 VAC supply, which inherently reduces input current per phase, lowers harmonic distortion on the plant bus, and eliminates the need for large bulk capacitance to bridge half-wave rectification gaps. The result is a power supply whose output ripple remains below 150 mV peak-to-peak under full 40 A load — a figure that directly determines the noise floor for analog signal conditioning circuits sharing the same 24 VDC rail.

In a SIMATIC S7-1500 or ET 200MP distributed I/O station, the 6EP1436-3BA00 typically feeds the 24 VDC load bus that powers CPU modules, interface modules, and up to 32 peripheral I/O modules simultaneously. At 960 W total output power, it provides sufficient headroom to absorb inrush transients from solenoid valve banks and motor contactors without triggering the internal overload fold-back circuit. The unit’s output voltage is adjustable from 22.8 V to 26.4 V via a front-panel potentiometer, allowing field engineers to compensate for cable voltage drop across long 24 VDC distribution runs in large panel enclosures.

The DC OK signaling contact — a floating relay output rated at 24 VDC / 0.5 A — provides a hardware-level health signal that can be wired directly into a SIMATIC CPU digital input or a safety PLC’s diagnostic channel. This allows the PLC program to execute a controlled shutdown sequence or trigger an alarm before the output voltage drops below the 18 V undervoltage lockout threshold, preserving data integrity in retentive memory areas and preventing undefined states in connected field devices.

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Technical Parameters

Hardware Logical Analysis

The 6EP1436-3BA00 employs an active power factor correction (PFC) front-end stage operating at a switching frequency of approximately 70 kHz. This PFC stage shapes the input current waveform to follow the sinusoidal voltage envelope of each of the three input phases, achieving a power factor of ≥ 0.99. The practical consequence for plant electrical engineers is a significant reduction in reactive current demand on the distribution transformer, which translates to lower I²R losses in the supply cabling and reduced harmonic content injected back into the plant bus — a compliance requirement under IEC 61000-3-2 Class A for equipment above 75 W.

The DC-DC conversion stage uses a phase-shifted full-bridge topology operating on the rectified and PFC-conditioned DC link voltage (typically 650–700 VDC internal bus). Phase-shifted PWM control allows zero-voltage switching (ZVS) of the primary-side MOSFETs, which eliminates switching losses at turn-on transitions and is the primary mechanism behind the ≥ 93% efficiency figure. The transformer operates at high frequency, keeping its core volume small and contributing to the compact 80 mm panel width.

EMC performance is addressed at multiple hardware layers. The input filter stage incorporates common-mode chokes and X/Y capacitors to suppress both differential-mode and common-mode conducted emissions, meeting EN 55011 Class B limits. The output stage includes a post-filter LC network that attenuates switching-frequency ripple to the ≤ 150 mV specification. The steel enclosure provides a Faraday shield against radiated emissions, and the DIN rail mounting clip establishes a low-impedance chassis ground path, which is critical in environments with variable-frequency drives (VFDs) generating high dV/dt transients on the ground plane.

The overload protection architecture uses a two-stage response: a constant-current limiting region that clamps output current at approximately 105–110% of rated current for sustained overloads, followed by a hiccup-mode shutdown if the fault persists beyond the thermal threshold. This behavior protects both the power supply and downstream wiring from sustained fault currents while allowing automatic recovery once the overload is cleared — a behavior that avoids nuisance manual resets in unattended remote installations.

Parallel operation is supported without additional load-sharing modules. The output voltage droop characteristic of each unit is matched at the factory, allowing two or more 6EP1436-3BA00 units to share load current within ±10% balance when connected in parallel. This architecture supports N+1 redundancy configurations where a second unit remains in hot-standby, taking over load seamlessly if the primary unit’s DC OK contact opens.

System Integration Benefits

• Deterministic DC Bus Stability: The active PFC stage decouples output regulation from input phase voltage variations of ±10%, ensuring the 24 VDC bus remains within ±1% regulation even during plant-wide load switching events that cause momentary input sags.
• Diagnostic Transparency via DC OK Contact: The floating relay output integrates directly into SIMATIC CPU DI channels or F-DI safety modules, enabling the PLC program to log power supply health events with millisecond timestamp resolution in the diagnostic buffer.
• Reduced Panel Thermal Load: At ≥ 93% efficiency, the 6EP1436-3BA00 dissipates approximately 67 W at full load — compared to 120–150 W for a comparable 85%-efficient unit — reducing the thermal management burden on the control cabinet and extending the service life of adjacent components.
• Scalable Current Architecture: Native parallel operation allows system architects to scale the 24 VDC bus from 40 A to 80 A or 120 A by adding units without redesigning the distribution topology or introducing active load-sharing controllers.
• Phase-Loss Ride-Through: The ≥ 20 ms hold-up time on phase loss allows the connected PLC to execute an orderly shutdown sequence, write retentive data to non-volatile memory, and de-energize outputs in a defined sequence before the DC bus collapses.
• Wide Operating Temperature Envelope: The −25 °C to +70 °C operating range covers outdoor enclosure installations in northern European winters and tropical process plant environments without derating, eliminating the need for enclosure heating or forced cooling in most deployments.
• ATEX Zone 2 Certification: The unit is certified for installation in Zone 2 explosive atmospheres (Category 3G), making it directly applicable to oil & gas wellhead panels, chemical plant junction boxes, and offshore platform control rooms without additional enclosure barriers.
• IEC 61131-2 Compliance: Output voltage and transient response characteristics conform to IEC 61131-2 requirements for PLC power supply inputs, ensuring compatibility with all SIMATIC CPU and I/O module power input specifications without derating calculations.

Quality Assurance & Global Logistics

Every 6EP1436-3BA00 unit supplied by siemensplc.com is sourced as genuine Siemens AG manufactured hardware. Units are procured through verified supply channels with full traceability to Siemens production batches. Prior to dispatch, each unit undergoes output voltage calibration verification, DC OK contact continuity check, and visual inspection of label authenticity and housing integrity. A 12-month warranty from shipment date covers manufacturing defects and functional failures under normal operating conditions, with replacement or credit resolution within 5 business days of confirmed fault diagnosis.

Logistics operations are based in Xiamen, China — a major international port city with direct air freight connections to DHL, FedEx, and UPS global hubs. In-stock units are dispatched within 1–2 business days of order confirmation. Standard international air freight transit times are 3–7 business days to Europe, North America, Southeast Asia, and the Middle East. Sea freight consolidation is available for bulk orders. Full export documentation is provided with every shipment: commercial invoice, packing list, certificate of origin, and where required, ATEX conformity declaration. HS code 8504.40 applies to this product class for customs classification purposes.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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