DC coil 72-125 V — pull-in margin and transformer loading
The 3RT2518-2XF40-0LA2: The DC coil is rated for 72 to 125 V DC. The pull-in voltage is 0.7 × rated value, so at a nominal 110 V DC bus the contactor pulls in reliably at 77 V — well within the typical battery sag during a station black-start sequence. The inrush current peak is 1.1 A; that spike loads the control transformer and the rectifier — if you are feeding multiple contactors from a common DC supply, sum the inrush peaks and check the transformer's regulation curve so the bus does not dip below the hold-in threshold. Hold-in power is lower than pull-in — the 0.7 factor applies to the initial pull-in only. Once sealed, the coil current drops to the holding value, which keeps the temperature rise inside the S00 envelope manageable even in a crowded 45 mm slot.
Switching capacity — AC motor and DC load break
For AC motor duty, the contactor is rated 2 hp at 230 V, 14 A at 480 V, and 11 A at 600 V. That derating is typical for DC arcs — the arcing time is 10-15 ms, and the DC arc extinguishes only when the current falls below the minimum arc current, so the contact gap and blowout design limit the DC rating. The main contacts are rated 20-12 A. This is the continuous thermal current (Ith) — the contactor can carry that current continuously in free air. In a sealed panel with multiple contactors side by side, derate per the manufacturer's grouping factor; the 45 mm width leaves little space for natural convection between units.
Spring terminals and wire range — panel wiring speed
The coil and auxiliary connections use spring-type terminals. The solid conductor range is 2×(0.5-1.5 mm²), 2×(0.75-2.5 mm²), and 2×4 mm². The main power terminals accept 2×(0.5-4 mm²) solid or stranded. Spring terminals eliminate the need for a screwdriver torque check — push the ferrule in until the cage clicks. For the 4 mm² power wires, use a ferrule sized for the strand class; the spring force is sufficient for Class 2 stranded but may not grip Class 5 flexible without a ferrule.
Mounting and clearance — DIN rail and enclosure fit
The height is 70 mm — check the DIN rail end-stop height if the rail is near the top of the enclosure.