S202-Z20 — 2-pole Z-curve MCB for semiconductor and sensitive loads
The ABB S202-Z20 is a 2-pole miniature circuit breaker rated 20 A with a Trip Curve Z characteristic, designed for DIN-rail mounting. Rated 277 VAC with a 6 kA interrupting capacity, this breaker is sized for branch-circuit protection in 480Y/277 V wye systems.
Trip Curve Z — what it means for your circuit
Trip Curve Z is the fastest standard magnetic trip characteristic available in the S200 series. It operates between 2× and 3× In (40–60 A for this 20 A breaker), compared to Curve C which trips at 5–10× In. This means the S202-Z20 clears a short-circuit fault in under 0.1 seconds at currents as low as 40 A — critical for protecting IGBT modules, diode bridges, and other power semiconductors that cannot survive even a single half-cycle of overcurrent. The trade-off is reduced tolerance for inrush. Motors, transformers, and capacitive loads that draw a brief startup surge above 40 A will cause nuisance tripping on a Z-curve breaker. Reserve this part for purely resistive or electronic loads where the peak fault current must be caught early.
Panel integration — DIN-rail footprint
Mounts on standard 35 mm DIN rail per EN 60715. The 2-pole housing occupies two 17.5 mm module widths (35 mm total) in the enclosure. Spring-cage terminals accept 0.5–25 mm² conductors; torque to 2.5 Nm per the terminal marking. The S200 series shares a consistent 17.5 mm per-pole footprint across all curve variants, so a panel originally specified with S202M-C63 or S203-D13 can accept the S202-Z20 in the same DIN-rail slot without rewiring the busbar or re-drilling the mounting plate.