The Siemens 5SM3646-4KK14 is a SENTRON-series residual current circuit breaker (RCCB) designed for 4-pole, 63 A circuits with a 300 mA Type B+ residual-current trip. The Type B+ classification means it detects smooth DC residual currents and high-frequency AC components — not just standard AC and pulsating DC — making it suitable for circuits with variable-speed drives, UPS systems, or EV charging equipment where non-sinusoidal fault currents are common.
The IP20 rating applies when the distribution board is installed with conductors connected — standard for enclosed panelboards, not for open wet-area mounting.
Thermal derating and ambient limits
Rated 63 A continuously at 40 °C and 45 °C ambient. Above that, the device derates linearly: 60.5 A at 50 °C, 58 A at 55 °C, 55.4 A at 60 °C, 52.9 A at 65 °C, and 50.4 A at 70 °C.