1250 A automatic transfer switch for critical source changeover
The Schneider Electric TA1AD3L12H4TPE is a TransferPacT automatic transfer switch rated 1250 A continuous at 400 V AC, 50/60 Hz, in a 3-pole configuration. It is designed for PC-class (IEC 60947-6-1) source changeover — meaning it switches between two power sources without intentional delay, and the contacts are rated for isolation (suitability for isolation confirmed). The AC-33B utilization category covers mixed motor and resistive loads, so this unit handles the combined inrush and running currents typical of a building or industrial feeder. Rated short-time withstand current (Icw) is 50 kA for 0.5 s and 70 kA for 0.1 s, giving selectivity headroom downstream. Short-circuit making capacity (Icm) reaches 105 kA as a switch-disconnector alone, or 154 kA with an upstream circuit breaker — a figure that matters when coordinating with the main incoming protection.
Installation and environmental fit
Fixed plate mounting, upside and downside connections are screwed terminals. The unit measures 540 mm wide × 391 mm high × 383.5 mm deep — sized for a dedicated enclosure section, not a DIN-rail footprint. Front face carries IP40 in auto mode; inside the enclosure the live parts meet IP20. Ambient operating range is -25 to 70 °C, storage -40 to 85 °C, with pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive).
Control and interface
Automatic operation with an LCD screen for local status and configuration. Signal contacts are configurable as 1 NO + 2 NC or 1 NC + 2 NO or 2 NO. Mechanical interlocking prevents both sources closing simultaneously. Padlockable in the OFF position. Mechanical durability is rated 10,000 cycles — a figure that governs maintenance intervals for frequent-transfer applications.