The Siemens SITAS 4AM3842-5AT10 converts 400V AC three-phase line voltage to 230V AC single-phase for auxiliary power circuits, delivering 0.7A at 160VA continuous. It serves as the front-end step-down stage in control panels where 230V is needed for DIN rail switch-mode power supplies, cabinet lighting, cooling fans, and service socket outlets — all fed from a 400V three-phase incomer without a separate 230V distribution feed.

400V Three-Phase Line to 230V Single-Phase Auxiliary Power

Connected across two phases of a 400V supply, the transformer provides a 230V single-phase output that mirrors standard European single-phase mains. This allows control panels with a 400V three-phase incomer to generate their own 230V auxiliary supply internally — feeding 24V DC power supplies, temperature controllers, panel illumination, and HVAC damper actuators — eliminating the need to pull a separate 230V neutral-referenced feed to the enclosure.

490VA Surge Rating for Auxiliary Load Inrush

Switch-mode power supplies draw high inrush current during initial capacitor charging, and small fan or pump motors present startup surges several times their running current. The 490VA S6 short-time rating absorbs these inrush events while maintaining stable 230V output for other auxiliary loads sharing the same transformer secondary.