The Siemens 3RT7036-1AL20 is a size S2 contactor from the SIRIUS family, with three normally-open main poles rated for AC-3 switching up to 690 V. Front protection is IP20 — safe for finger contact in a closed panel. The terminal area is rated IP00, meaning the connection points are exposed; standard practice is to keep this inside a locked enclosure or behind a cover.
Terminals and wiring
Both main and auxiliary/control circuits use screw-type terminals. The main current circuit accepts 2x (0.5 to 1.5 mm²) solid or stranded, or 2x (0.75 to 2.5 mm²). Finely stranded wire needs core-end processing (ferrules) for the same cross-sections. That's a standard panel-builder detail — no special crimp tool required beyond what's already on the bench. The product extension allows adding an auxiliary switch block, which is useful when you need feedback contacts for a PLC input or a status signal back to the control system.
Coil and switching performance
The magnet coil draws 0.76 W to close and 0.35 W to hold at DC — low holding power means less heat in a densely packed cabinet. Control supply voltage is AC type. Maximum switching rate is 800 operations per hour under AC-3 duty, dropping to 250 per hour under AC-4 (plugging/reversing). That's enough for most conveyor or pump cycling; if you're jogging a motor repeatedly, stay under the AC-4 limit or the contactor will overheat. Auxiliary contacts are rated for PLC-level signals — 17 V, 5 mA — so you can wire them directly to a digital input card without a separate interface relay. That saves a terminal and a DIN-rail slot.
Protection coordination
For type of coordination 2 (limited damage under short circuit), the required upstream fuse is a gL/gG NH 3NA rated 80 A. For type of coordination 1 (no damage to the contactor, but the starter may need replacement), the fuse can go up to 160 A. This matters when you're matching the contactor to an existing motor branch circuit — verify which coordination type your panel design calls for.