Siemens 5SY7302-8CC — D-curve MCB for motor and transformer branch circuits
Three-pole design (3P) with combined top and bottom terminals, quick-assembly mounting, and any-position installation. The 54 mm width occupies 3 modular units on a DIN rail.
D-curve trips between 10× and 20× In (20–40 A magnetic release), sized for motor starting and transformer energisation where a C-curve would nuisance-trip on inrush. The 2 A rating at 35 °C derates to 1.89 A at 40 °C and 1.71 A at 55 °C — if your enclosure runs hot, factor the thermal curve into the branch-circuit sizing. The 50 kA SCCR at 440 V AC per IEC 60947-2 covers most industrial supply points; verify against your transformer kVA and upstream breaker let-through.
D-curve selectivity and coordination note
For selectivity studies: the D-curve's magnetic threshold at 20–40 A means downstream C-curve MCBs on lighting or control circuits will clear before this breaker trips on a low-level fault. Upstream, verify the 50 kA rating against your transformer's short-circuit capacity. The 440 V AC rating covers 400 V and 415 V systems common in European and Asian industrial plants; 50/60 Hz rated.