Siemens SENTRON 5SY7240-7CC — 40 A C-Curve 2-Pole MCB
Two poles, 36 mm wide (2 MW), it snaps onto DIN rail and suits panel builds where 40 A branch protection is needed on lighting, motor, or distribution subfeeds. Breaking capacity is 25 kA per IEC 60947-2 and 5 kA per UL 1077 / CSA C22.2 No.235 — enough for most industrial distribution boards with high fault current.
The C-curve trips on short-circuit between 5× and 10× In (200–400 A) — right for motor or capacitive loads that draw a brief inrush but not for highly inductive switching where a D-curve might be preferred. At 400 V AC the breaker clears faults up to 25 kA. Under UL 1077 the rating drops to 5 kA — if your panel requires a UL 489 listed breaker, this is a supplementary protector per UL 1077, not a branch-circuit rated device. Verify the listing class your local code demands. Wire range accepts 0.75–35 mm² solid or stranded. Torque terminals to 2.5–3.5 N·m. Combined terminals top and bottom allow through-wiring or daisy-chaining busbars without extra lugs.
Snap-on DIN rail mount, any position. The 36 mm width matches two standard modular units. Installation depth is 70 mm; total depth 76 mm includes the handle. Sealable for lockout/tagout — padlock through the toggle hole. Ambient range -25 to +55 °C, storage -40 to +75 °C. Halogen-free and silicon-free construction for sensitive environments like clean rooms or semiconductor fabs.