The 5SY4303-7 carries a dual-rated breaking capacity: 10 kA per EN 60898 at 400 V AC, and 35 kA per IEC 60947-2 — the higher figure applies when the MCB is installed in an industrial distribution board where the prospective fault current exceeds 10 kA, provided the upstream transformer and cable impedance allow it. C-trip characteristic means the magnetic release picks up between 5× and 10× In — the right choice for motor-starter or transformer primary protection where inrush current would nuisance-trip a B-curve device, but still fast enough to clear a bolted fault before the downstream contactor welds shut.
AC and DC voltage envelope
Rated 400 V AC for multi-phase operation, 440 V AC for both multi-phase and single-phase operation — the 40 V headroom above the nominal 400 V line accounts for the steady-state voltage rise on a lightly loaded transformer secondary. DC rating is 60 V per pole, with a maximum operating voltage of 72 V DC — the 12 V margin above the nominal rating is the ceiling before the arc-extinction gap in a single-pole DC break becomes unreliable.
Lifecycle and sourcing — active, quoted to order
Current-production status (lifecycle stage: current). No successor or phase-out notice on record — the 5SY4303-7 is the standard catalogue variant for the 3-pole C-curve 10 kA position in the SENTRON family.
IP20 with connected conductors — the terminals are finger-safe when wired, but the enclosure does not seal against water ingress. Sealable (padlockable) handle for lockout/tagout compliance. Ambient temperature range -40 °C to 75 °C, with humidity derating above 55 °C: max 95% RH at 55 °C, falling to 35% RH at 75 °C.