What it is and where it fits
The Siemens SIRIUS 3RT1026-1AL20-ZW98 is a power contactor in the S0 frame size, designed for switching motor loads in industrial control panels. It mounts on a 35 mm DIN rail per DIN EN 50022, with a 45 mm width that slots into standard panel layouts without crowding adjacent devices. Rated for AC-2 duty at 11 kW on a 400 V supply, this contactor handles wound-rotor motor applications where starting current stays moderate. The AC-4 rating of 15.5 A at 400 V covers reversing and inching duty cycles — the kind of stop-start abuse a conveyor or crane sees shift after shift.
What the ratings mean in the panel
The S0 frame carries a mechanical life of 10 million operations, which is the contactor's structural endurance before wear-out — not the electrical life under load, which will be lower depending on the switching duty. For AC-4 reversing duty at full rated current, expect the electrical life to be a fraction of that figure; plan spares accordingly if the application cycles frequently under load. Short-circuit coordination is specified with two levels: Type 1 coordination allows the contactor to be damaged but safe to operate after clearing a fault, using a 100 A gL/gG fuse. Type 2 coordination, which keeps the contactor usable after a fault, requires a 35 A gL/gG fuse. If the panel spec demands Type 2 — typical for critical processes where downtime for contactor replacement is unacceptable — the upstream fuse must be limited to 35 A. The auxiliary contact block is rated for 10 A at 24 V (AC-12), which covers most PLC input or relay coil loads. At 230 V the rating drops to 6 A, and at 400 V to 3 A — the arc extinction limits for the same contact gap. If you are switching an inductive load like a small contactor coil at 230 V, stay under 6 A or add a snubber.
Lifecycle and sourcing
The operating temperature range of -25 to +60 °C covers most indoor panel environments, including unventilated enclosures near process heat. The IP20 front protection means it is sealed against finger contact but not against dust ingress — mount it inside a panel with a gasketed door if the ambient air carries cement dust or grain fines.
Wiring and integration notes
Side-by-side mounting is permitted without derating, which means the 45 mm width per pole is the total panel footprint — no extra air gap needed between contactors. The 6 mm clearance to grounded metal on the side is the minimum for the arc chamber; respect that if mounting near a panel wall or another device's live parts.