SIRIUS S0 power contactor for motor switching at 50 Hz
The Siemens 3RT1026-1AP04-1AA0 is a SIRIUS S0-frame power contactor with a 50 Hz coil rated at 230 V. It carries three normally-open main contacts and switches motor loads in AC-4 duty up to 15.5 A at 400 V — that's the rating that governs reversing or inching applications where the contactor makes and breaks stalled-rotor current. For AC-2 at 400 V it handles 11 kW, covering slip-ring motor starting. Mounting is screw-fix or snap-on onto a 35 mm DIN rail per DIN EN 50022. The 45 mm width and 85 mm height fit standard S0 panel cutouts, and the 140 mm depth leaves room for wiring gutters. Side-by-side mounting is permitted without derating, which keeps the fill factor tight in a crowded enclosure.
Wiring and terminal capacity
Main circuit terminals are screw-type, accepting 2x (1 to 2.5 mm²) stranded or 2x (2.5 to 6 mm²) solid, with a maximum of 2x 10 mm². The auxiliary/coil terminals take 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Strip length and ferrule sizing follow standard practice — 8 mm for the smaller terminals, 10 mm for the main power wires. For Type 1 coordination (no damage to the contactor under short circuit), the required upstream fuse is gL/gG 100 A. For Type 2 coordination (limited weld risk), use a 35 A gL/gG fuse. That selectivity choice affects panel SCCR and should be locked in at the BOM stage.
Environmental limits and approvals
Operating temperature range is -25 to +60 °C during operation. Pollution degree 3 means it tolerates conductive dust and humidity typical of industrial control panels — no conformal coating required for most environments. Maximum operating altitude is 2 000 m without derating. Front protection is IP20 (finger-safe); the terminal area is IP00, so live parts are exposed below the gland plate — standard for panel-mount contactors. Mechanical endurance is rated at 10 million operating cycles typical. The coil operating range at 50 Hz is 0.8 to 1.1 times the rated voltage (230 V), so it picks up reliably down to about 184 V and holds in up to 253 V.