Siemens 6ES5951-7LB21 is a SIMATIC S5 power supply unit (951 series) designed as a spare part for the S5-115U/H controller family. It accepts 120/230 V AC input and provides a regulated 5 V DC output at up to 3 A, powering the S5-115U/H system without any backup battery. This module is used in legacy Siemens S5 installations where a 951-series supply is required to run the CPU and associated peripherals. Ensure compatibility with S5-115U/H units to match the 951 power rail requirements.
