Siemens 6ES7405-0KA02-0AA0 PS 405 Power Supply

The Siemens 6ES7405-0KA02-0AA0 is a power supply module for the SIMATIC S7-400 programmable logic controller system. Designated as PS 405, this unit converts a wide range of DC input voltage (24-60V DC) to a regulated 5V DC output with 10A capacity, supplying the S7-400 backplane bus and connected modules. It is designed for high-availability applications and can be used in redundant configurations.

Technical Specifications

Input voltage: 24-60V DC (continuous range, including battery-powered systems). Input current: max 3.5A at 24V DC, 1.5A at 60V DC. Output: 5V DC nominal, ±2% regulation, output current 10A continuous (sufficient for up to 8-10 S7-400 modules depending on consumption). Ripple < 50 mVpp. Power loss: typical 45W. The module provides short-circuit protection (latching, auto restart after fault removal), overload protection, and overvoltage protection. Redundancy capability: two PS 405 modules can be connected in parallel for 1+1 redundancy (requires external redundancy adapter 6ES7407-0DA02-0AA0). LED indicators: INTF (internal fault), BAF (battery fault), 5V DC (output OK). The module occupies one slot in the S7-400 rack (single-width). Operating temperature: 0°C to 60°C. Storage temperature: -40°C to 70°C. Protection rating IP20. Weight approx. 1.2 kg.

Key Features

• Wide DC input range 24-60V DC for industrial and marine applications

• Output 5V DC, 10A for S7-400 backplane

• Redundancy ready (parallel connection of two units)

• Short-circuit, overload, and overvoltage protection

• LED diagnostics for internal fault, battery fault, output status

• Battery backup connection for RAM retention (external battery)

• Active current sharing in redundant configuration

• Compatible with all S7-400 racks (UR1, UR2, UR2-H, CR2, etc.)

Redundancy and High Availability

For fail-safe applications, two PS 405 modules can be connected via a redundancy adapter (6ES7407-0DA02-0AA0) that combines outputs and includes decoupling diodes. When one power supply fails, the other automatically takes the full load without interruption. The "active current sharing" ensures even load distribution during normal operation, prolonging life. The redundancy adapter must be mounted externally near the power supplies.

Battery Backup

The PS 405 includes terminals for connecting an external backup battery (e.g., 6ES7971-0BA00). The battery maintains the user program and data in the CPU's RAM when the main power is off. The LED "BAF" (battery fault) indicates low battery or missing battery. The charging circuit is built into the power supply; typical recharge time is 24 hours for a fully discharged battery. The battery type is lead-acid or NiMH, 24V nominal.

Installation and Wiring

The PS 405 mounts in the leftmost slot of an S7-400 rack (slot 1). It connects to the backplane via the rack connectors. No external load is required on the 5V output; the backplane distributes power to other modules. Input terminals (L+, M) accept 24-60V DC. A protective earth (PE) connection is required for safety. Use 2.5 mm² wire (AWG 14). The unit also provides an auxiliary output (24V DC, 1A) on terminals (AUX) for powering small field devices (e.g., the redundancy adapter).

Diagnostics and LEDs

Three LEDs on the front panel: "INTF" (red) indicates internal fault (overvoltage, overtemperature, or internal error). "BAF" (yellow) indicates battery fault (missing, low voltage, or defective). "5V DC" (green) indicates output voltage is within specification. If the 5V LED is off, either the power supply is off, or a short circuit on the backplane has shut down the output. All diagnostic information is also readable via the CPU's diagnostic buffer (if connected).

Applications

The PS 405 is intended for S7-400 systems in applications requiring DC power sources such as battery-backed plants, solar installations, marine vessels, or facilities where 24V DC is the primary distribution voltage. It is also used in redundant power configurations for critical processes (e.g., chemical plants, power generation).

Standards and Certifications

The PS 405 complies with CE, UL 508, CSA C22.2, and ATEX (Zone 2) for hazardous locations. It meets EN 61131-2 (PLC equipment) and EN 61000-6-2 (industrial immunity). Input-to-output isolation is 1500V AC. The module is RoHS compliant.

Conclusion

The Siemens 6ES7405-0KA02-0AA0 PS 405 power supply provides reliable DC-DC conversion for S7-400 systems, especially in environments with 24-60V DC power. Its wide input range, redundancy capability, and diagnostic features make it suitable for demanding industrial automation.