What it is and what it does
The Siemens 3RT1023-1AT60 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads in control panels. It carries three normally-open main contacts and is rated for 4 kW at AC-2 duty at 400 V, which covers slip-ring motor starting and plugging applications. For resistive loads (AC-12), it handles up to 10 A.
Mounting and integration
Mounts via screw or snap-on onto a 35 mm DIN rail per EN 50022. The 45 mm width and 85 mm height fit standard panel layouts; depth is 91 mm. Side-by-side mounting is permitted, with 6 mm clearance at the side for heat dissipation. Front face carries an IP20 rating; the terminals themselves are IP00, so live parts are exposed — keep the panel door interlocked or use a finger-safe cover.
Wiring and conductor sizing
Main circuit terminals are screw-type, accepting solid conductors from 2x 0.5 mm² up to 2x 4 mm², and stranded from 2x 1 mm² up to 2x 10 mm². For AWG, that's 2x 16–12 solid or 2x 14–10 stranded, with a single 8 AWG maximum. The coil circuit uses separate smaller terminals; verify the 24 VDC coil draw against your PLC output card — the contactor itself is rated for 10 A at 24 V on the auxiliary side.
Coordination and protection
For Type 1 coordination (no damage to the contactor, but it may need replacement after a fault), use a gL/gG fuse rated up to 63 A. For Type 2 coordination (contactor remains usable after a fault), the fuse must be limited to 25 A gL/gG. This matters when you're designing for minimal downtime — Type 2 keeps the line running after a short-circuit event without swapping the contactor.