Auxiliary contactor for control-circuit switching
It is designed for control-circuit switching in panels and motor starter assemblies, extending the contact count of a main contactor or providing isolated signal routing. The coil draws 3.2 W during both closing and holding, so the power supply needs to cover that steady draw continuously.
Contact ratings and switching capacity
The 4 NO contacts are rated for resistive loads at various voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. For inductive DC loads the ratings drop further — 1 A at 110 V and 0.27 A at 220 V. That means the 3RH1440-1BW40 handles typical 24 V DC pilot-duty circuits easily, but at higher DC voltages the current capacity is limited to fractional amps. The contacts are rated for 10g / 5 ms and 5g / 10 ms shock resistance, and the contact reliability spec calls for one incorrect switching operation per 100 million operations at 17 V, 1 mA — a solid figure for dry-circuit PLC inputs.
The size S00 footprint — 57.5 mm high, 90 mm wide, 72 mm deep — fits standard panel layouts. Wire termination accepts solid conductors: 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², or 2x 4 mm² (or AWG equivalents 2x 20–16, 2x 18–14, 1x 12).