SITOP buffer module, 4-output, 99% efficiency
The Siemens 6EP1961-2BA21 is a SITOP buffer module that bridges supply dips with four controlled DC outputs. It snaps onto a DIN rail EN 60715 35x7.5/15 and occupies 72 mm width, 80 mm height, 72 mm depth — a compact footprint for control-panel integration. Input accepts 22-30 V DC; output follows Vin minus roughly 0.2 V, with a controlled DC voltage curve. Efficiency hits 99 %, so nearly all input power passes through to the load, minimizing thermal waste inside the enclosure.
Four outputs let this module buffer multiple loads — PLC, I/O slices, fieldbus power supplies — from a single buffer stage. The overcurrent protection trips at 1.0-1.5× set value with a 5-second delay; a faster current limitation kicks in at 1.5× set value with roughly 100 ms switch-off. That dual curve means nuisance trips from inrush are unlikely, but hard shorts clear quickly. The remote reset input (non-electrically isolated, signal high above 15 V) allows automated recovery after a fault, useful for remote or unattended panels. The 50 mm top clearance and 50 mm bottom clearance are the minimum free air space above and below the module for natural convection cooling — respect those in the panel layout to avoid derating.