The Siemens 3RT1036-3AL20-ZX95 is a SIRIUS power contactor in size S2, rated for 22 kW at 400 V in AC-2 duty (slip-ring motor switching). For a 22 kW slip-ring motor on 400 V three-phase, this contactor lands on the critical path; anything smaller and you're derating into the next outage window.
DIN Rail Fit and Terminal Reality
Side-by-side mounting is permitted, so zero gap between contactors on the rail, but watch the heat buildup at AC-3 max 800 switching cycles per hour.
Terminal Capacity and Wire Prep
Solid wire: 2x (0.25 to 2.5 mm²). Stranded: 2x (0.75 to 25 mm²). The combined solid-or-stranded range is 2x (0.75 to 16 mm²) — that's the practical working range for panel builders. Strip and torque per the terminal marking; the 25 mm² stranded upper end is for the main power feed, not the control loop.
Environmental and Protection Class
Front face rated IP20; the terminal area is IP00 — that's typical for a panel-mounted contactor where the enclosure provides the overall seal.
Switching Performance and Mechanical Life
Mechanical life is typical 10,000,000 operations. At 50 Hz the operating range is 0.8 to 1.1 times rated voltage; at 60 Hz it's 0.85 to 1.1. The auxiliary contact ratings at 24 V are 10 A, at 60 V 2 A, at 110 V 1 A, at 220 V 0.3 A — these govern the control circuit load, not the main power path.
Switching Frequency by Duty Class
Maximum switching frequency varies by duty: AC-1 (resistive) at 1000 cycles/hour, AC-2 (slip-ring motor) at 400 cycles/hour, AC-3 (squirrel-cage motor) at 800 cycles/hour, AC-4 (plugging/inching) at 300 cycles/hour. For a conveyor drive cycling at 600 per hour, the AC-3 rating clears it; for a crane hoist with reversing starts, the AC-4 ceiling of 300 is the hard limit.