SIRIUS coupling contactor, S2 frame — what the ratings mean for fit
The Siemens 3RT2036-3KB44-3MA0 is a SIRIUS coupling contactor in the S2 frame size, designed for applications where a main contactor needs to be electrically isolated from the control circuit — typically used to switch loads like motors or heaters in a panel while keeping the coil circuit separate for safety or logic reasons. The 24 VDC coil draws a 2.6 A inrush peak and holds at 6 A at rated voltage, so the control transformer or DC supply must be sized for that surge, not just the sealed current. Spring-type terminals (cage clamp) on the magnet coil and main contacts accept 2x (0.5... 2.5 mm²) solid or stranded, which matches standard control wiring practice and eliminates the need for ferrule tightening checks during commissioning. The contactor measures 55 mm wide by 114 mm high by 178 mm deep, and mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The mounting position is flexible — +/-180° rotation on a vertical surface, and can be tilted forward/backward by +/-22.5° — which helps when fitting into tight or non-standard panel layouts. Clearance distances are tight: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side, so it can be packed densely on the rail without excessive spacing. Main contacts rated for 18 A operational current in AC-3 duty, with 1 A minimum switching capability. Switching frequency: 1 000 cycles/h at AC-1, 800 at AC-3, 600 at AC-2, 250 at AC-4. The coil operates from -25 to +60 °C ambient and can be stored from -55 to +80 °C. The arcing time is 10 to 20 ms, and the DC dropout delay is 30 to 55 ms — useful to know when coordinating with downstream devices that need to drop out before the main contacts open.
Auxiliary contact ratings — what the voltage/current table tells you
This contactor variant ships without an auxiliary switch block (auxiliary switch: no), but the auxiliary contact ratings are listed for when a block is added. At 24 V rated value, the auxiliary contacts carry 6 A; at 48 V, 2 A; at 60 V, 2 A; at 110 V, 1 A; at 125 V, 0.9 A; at 220 V, 0.3 A; at 400 V, 3 A; at 440 V, 0.6 A. The 230 V rating is given as 10 hp, which is a motor load rating for the auxiliary contacts — unusual for auxiliaries, so verify the application before using them for motor switching. The 400 V 3 A rating is notable: it suggests the auxiliary contacts can handle a moderate inductive load at line voltage, useful for piloting another contactor coil.