Power supply for the S7-400 rack
The Siemens 6ES7405-0DA01-0AA0 is a SIMATIC S7-400 PS 405 4A power supply module that accepts a 24 V DC input and delivers a regulated 5 V DC output at 4 A to the backplane bus, plus a 24 V DC output at 0.5 A for the backplane bus. The module also provides a 48 V DC output rated at 1 000 mA and a 60 V DC output rated at 800 mA.
Backplane capacity and power budget
The 5 V DC backplane bus output is rated at 4 A maximum, which determines how many S7-400 I/O and interface modules this supply can support in the rack. Typical power loss is 16 W, with an active power input of 48 W. Short-circuit protection is included on the outputs, and the module is idling-proof per the design.
Mains buffering and backup
The supply holds up the backplane for 20 ms on a mains/voltage failure, which is sufficient to ride through most line dips without a UPS. Mains buffering per NAMUR recommendation is supported. An optional backup battery (1x lithium AA, 3.6 V / 2.3 Ah) can be fitted to retain the S7-400 memory contents during extended power outages.
Approvals and wiring
FM approval is listed for Class I, Division 2, Groups A, B, C, D T4 at ambient temperatures from 0 °C to 60 °C, making it suitable for installation in hazardous locations. Equipment protection class I requires a protective conductor connection. The power connection accepts 3x 1.5 mm² solid or stranded wire with end sleeve, with an external diameter of 3 mm to 9 mm.