What it is and what it does
The Siemens SIRIUS 3RH1140-2BB40-0TK1-ZX95 is an auxiliary contactor — a 24 V DC coil switching four normally-open (4 NO) instantaneous contacts in a size S00 frame. It's the part that extends the control logic of a motor starter or feeds status back to a PLC without pulling more load through the main contactor's aux block. Rated 10 A at 24 V, it's built for the control circuit, not the power legs.
What the ratings mean for fit
The 24 V DC coil draws 3.2 W to pull in and holds at the same 3.2 W — no drop in holding power, so the coil runs warm but steady. If you're swapping this into an existing panel, check that your 24 V DC supply can handle the inrush; the coil's closing power is the same as its holding power, which means no spike, but the steady draw is constant. The 4 NO contacts are rated by voltage: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, 1 A at 690 V. That derating curve matters — at 400 V line-to-line you're limited to 3 A through the aux contacts, so don't try to switch a 5 A pilot load at that voltage.
Where it fits in the panel
Size S00 frame, 45 mm wide, 60 mm tall, 73 mm deep. Screw and snap-on mounting to DIN rail. Mounting position is flexible — +/-180° rotation on a vertical surface, and can be tilted forward/backward by +/-22.5°. That's useful when you're shoehorning it into a crowded enclosure and need to orient the contactor to clear a busbar or duct. Wire termination accepts 2x (0.25... 2.5 mm²) solid or stranded — standard control-circuit sizing. IP20 on the front, so it's protected against finger contact but not washdown; keep it inside the enclosure.
Compliance and approvals
Surge voltage resistance rated at 6 kV, pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive — typical for industrial control panels). Contact reliability is specified as one incorrect switching operation per 100 million operations at 17 V, 1 mA — that's the low-energy signal reliability; if you're switching dry contacts into a PLC input, this contactor handles it. RoHS compliance date of 01.07.2006 is on record. Reference code per IEC 81346-2 is K (contactors, relays).