Siemens 6ES7407-0KR02-0AA0 Power Supply Module – PS407 S7-400

Siemens 6ES7407-0KR02-0AA0 PS407 10A — Backbone Power Architecture for SIMATIC S7-400 Control Systems

The 6ES7407-0KR02-0AA0 is the highest-rated standard power supply module in the Siemens PS407 series, engineered specifically for the SIMATIC S7-400 platform. Rated at 24 V DC / 10 A (240 W continuous), it serves as the primary energy source for the S7-400 backplane bus, supplying regulated 5 V DC to CPUs, communication processors, and I/O modules while simultaneously delivering 24 V DC to field-side sensors and actuators. Its wide-range AC input (85–264 V AC, 47–63 Hz) eliminates the need for external step-down transformers in international deployments, making it the default specification for global project standardization and spare-parts unification programs.

The PS407 10A occupies Slot 1 or Slot 2 of any S7-400 rack (UR1, UR2, UR2-H, CR2, CR3) and interfaces directly with the backplane bus via a dedicated power connector — no software configuration required. The module’s internal architecture separates the AC input stage, power factor correction (PFC) circuit, isolated DC/DC converter, and backplane bus driver into discrete functional blocks, each with independent thermal management. This segmented design confines fault propagation: a transient on the AC input does not propagate to the 5 V bus, and a backplane overcurrent event does not collapse the 24 V output rail.

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Technical Parameters

Hardware Logical Analysis

The internal power conversion chain of the 6ES7407-0KR02-0AA0 follows a three-stage topology: active power factor correction (PFC) → phase-shifted full-bridge (PSFB) DC/DC converter → synchronous rectification output stage.

Stage 1 — Active PFC: The front-end boost converter maintains the input current waveform in phase with the AC voltage, achieving a power factor above 0.95 across the full input range. This reduces harmonic injection into the facility power grid, a critical requirement in process plants where multiple drives and power supplies share a common bus. The PFC stage also pre-charges the bulk capacitor bank to approximately 380–400 V DC, providing the energy reservoir that sustains the 20 ms hold-up time during voltage dips.

Stage 2 — Phase-Shifted Full-Bridge Converter: The PSFB topology operates at a fixed switching frequency (typically 100–150 kHz), using zero-voltage switching (ZVS) on the primary-side MOSFETs to minimize switching losses and radiated EMI. The high-frequency transformer provides galvanic isolation between the AC input and the 24 V DC output, with a creepage distance and clearance compliant with IEC 60664-1 Pollution Degree 2. The transformer’s leakage inductance is tuned to serve as the resonant element for ZVS, eliminating the need for a separate resonant inductor and reducing component count.

Stage 3 — Synchronous Rectification & Output Filter: The secondary side uses synchronous rectification (SR) MOSFETs instead of Schottky diodes, reducing conduction losses by approximately 60 % at full load. The LC output filter is dimensioned to limit ripple to ≤ 150 mV peak-to-peak across a 20 MHz measurement bandwidth, ensuring clean supply rails for the S7-400 CPU’s analog reference circuits and communication interfaces.

EMC Design: A multi-stage EMI filter on the AC input (common-mode choke + X/Y capacitors) attenuates conducted emissions to comply with EN 55011 Class A limits. The module’s steel enclosure provides a Faraday shield against radiated emissions, and all internal signal lines are routed away from switching nodes to prevent capacitive coupling. The backplane connector is shielded and impedance-matched to the S7-400 bus specification, preventing reflections that could corrupt high-speed data transfers between CPU and I/O modules.

Redundancy Arbitration Logic: When two PS407 10A modules are installed in parallel, each module’s 24 V output is connected to the common bus through an internal isolation diode (forward voltage ≈ 0.4 V at 10 A). The module with the marginally higher output voltage supplies the majority of the load current; the second module remains in a warm-standby state, contributing a small balancing current. If the primary module fails (output collapses), the secondary module’s diode becomes forward-biased within one switching cycle (< 10 µs), and the bus voltage drops by only the diode forward voltage — well within the CPU’s input voltage tolerance. No external relay or switchover logic is required.

System Integration Benefits

• Deterministic Bus Voltage Stability: The regulated 5 V backplane output maintains ± 1 % tolerance under dynamic load steps (e.g., simultaneous activation of multiple digital output modules), preventing CPU clock jitter caused by supply rail fluctuation.
• Zero-Configuration Rack Integration: The module is recognized automatically by the S7-400 rack upon insertion; no STEP 7 or TIA Portal hardware configuration entry is required for the power supply itself, reducing commissioning time.
• Transparent Fault Diagnostics via LED Matrix: The four-LED panel (INTF, EXTF, DC5V, DC24V) provides immediate visual fault classification without requiring a connected programming device — maintenance technicians can isolate fault type (internal vs. external, 5 V bus vs. 24 V output) in under 30 seconds.
• ATEX Zone 2 Compliance: The module carries ATEX certification for use in areas with occasional explosive gas atmospheres (Zone 2, Group IIC), enabling direct installation in petrochemical and offshore control panels without additional enclosure upgrades.
• Wide-Range Input Eliminates Transformer Overhead: A single SKU covers 85–264 V AC input, removing the need for site-specific transformer variants in multinational plant rollouts and reducing spare-parts inventory by up to 50 % for global OEMs.
• N+1 Redundancy Without External Components: Parallel redundancy is achieved by installing a second PS407 10A in Slot 2 — no external ORing module, relay panel, or UPS bypass switch is required, reducing panel footprint and wiring complexity.
• Long Service Life Aligned with S7-400 Platform: With an MTBF exceeding 300,000 hours under IEC 61709 reference conditions, the module’s expected service life exceeds 34 years at 100 % duty cycle, matching the extended lifecycle support commitment Siemens provides for the S7-400 platform.
• Compatibility with S7-400H High-Availability Systems: The module is fully validated for use in S7-400H redundant CPU configurations, where both racks require independent, isolated power supplies. The PS407 10A’s isolation architecture prevents ground loops between redundant racks.
• Overtemperature Protection Preserves System Uptime: An internal NTC thermistor monitors the heatsink temperature; if the threshold is exceeded, the module reduces output current in a controlled ramp rather than triggering an abrupt shutdown, giving the CPU time to execute a safe-state routine before power is lost.
• Standardized Mechanical Form Factor: The 50 mm wide module occupies a single slot in any S7-400 rack, preserving adjacent slots for additional I/O or communication modules and maintaining full rack density.

Quality Assurance & Global Logistics

Every 6ES7407-0KR02-0AA0 unit shipped from our Xiamen facility undergoes a structured incoming inspection protocol before it enters stock:

• Visual & Nameplate Verification: Physical inspection of housing integrity, connector pin condition, and nameplate data (MLFB, serial number, hardware revision, date code). Serial numbers are cross-referenced against Siemens Industry Mall records where accessible.
• Powered Functional Test: Each unit is energized at 220 V AC and loaded to 50 % rated current. Output voltage (24 V DC ± 1 %), ripple (≤ 150 mV), and all four diagnostic LEDs are verified against factory specification.
• Insulation Resistance Test: Hi-pot test at 1,500 V AC between input and output for 1 minute, confirming transformer isolation integrity.
• Anti-Static Packaging: Units are sealed in anti-static poly bags, cushioned with EPE foam inserts, and packed in double-wall corrugated cartons rated to ISTA 2A transport standards.

Logistics from Xiamen, China: Xiamen is a major international port city with direct air freight connections to Europe, North America, Southeast Asia, and the Middle East. Standard export shipments are dispatched within 1–2 business days of order confirmation via DHL Express, FedEx International Priority, or UPS Worldwide Expedited. Typical transit times: Europe 3–5 days, North America 4–6 days, Southeast Asia 2–3 days. All shipments include a commercial invoice, packing list, and certificate of origin. For orders requiring ATEX documentation or third-party inspection (SGS, BV), please specify at the time of inquiry.

Warranty: 12 months from the date of shipment. DOA (Dead on Arrival) units are replaced free of charge within 48 hours of confirmed receipt of the defective item. Warranty claims are processed via email with photographic evidence of the fault condition.

Contact Information

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