The Siemens SITAS 4AM2642-5AT10 bridges the gap between the ultra-compact 25 VA class and the 100 VA workhorse range. Rated 40 VA, it converts 400 V AC mains to 230 V AC control voltage — sufficient for a small group of control relays, a contactor coil, or an auxiliary power supply for panel instruments. The three ±5% primary taps (380/400/420 V) allow precise matching to site voltage conditions. At 80 × 68 × 75 mm and approximately 1.0 kg, it fits in panels where a 4AM3442 (100 VA) would be oversized and a 4AM2342 (25 VA) would be underpowered.

Key Features

• 400 V to 230 V step-down — ideal for small control relay groups
• ±5% primary taps (380/400/420 V) for supply matching
• 40 VA — the sweet spot between 25 VA and 100 VA classes
• Compact 80 × 68 × 75 mm, ~1.0 kg, EI 66 core
• 76% efficiency, 50/60 Hz, IP00
• UL/CSA recognized, screw/tab terminals, DIN rail or screw mount

Technical Data

Applications

Small to medium control panels: powering 2–4 control relay coils, a single motor contactor holding circuit, auxiliary power for panel cooling fans and indicators, and distributed I/O station control supplies. The 40 VA rating fills the gap where 25 VA is insufficient but 100 VA would be excess capacity and cost.