The Siemens 5SM1314-6BA is a 2-pole FI (RCD) protector, Type A, rated 40A with 30mA sensitivity at 230V. The Type A designation means it detects sinusoidal AC residual currents plus pulsating DC residual currents — the standard requirement for circuits feeding single-phase electronics, switched-mode power supplies, and appliances with rectifier stages. The 30mA trip threshold provides personal protection against direct contact (shock) in residential, commercial, and light industrial final circuits.
The 55mm diameter of the residual-current transformer coil is internal — the overall device footprint is the standard 36mm per TE, so two modules wide. That keeps the panel fill factor predictable: a 24-way distribution board takes 48 modules of this type per row. Spring-cage or screw terminals are typical for this series; the 40A rating accepts conductors up to 16mm² for the incoming supply.