Panel fit and protection profile
The Curve K trip profile provides magnetic tripping between 8 and 12 times rated current — this makes it suitable for protecting circuits with moderate inrush, such as motor starters, transformers, or solenoid valve banks, where a standard B-curve would nuisance-trip on startup. Rated at 277 VAC with a 10 kA interrupting capacity, the S202MR-K4 handles fault currents typical in commercial lighting and small motor branch circuits. For a panel OEM wireman, the DIN rail footprint keeps fill factor predictable; two poles take 36 mm of rail width (standard 18 mm per pole), so plan gland plate space accordingly.
For a site electrical engineer working on fault coordination: the 10 kA interrupting rating at 277 VAC gives headroom for most downstream faults in a 277/480 V lighting panel. Curve K's magnetic trip threshold (8–12x In) means this breaker will hold through a motor start but trip fast on a bolted fault — useful for achieving Type 2 coordination with a contactor or soft starter downstream. No single point of failure here if the upstream device is properly coordinated.