The Siemens 5SU1353-6KV20 is an FI/LS combination unit (RCD + MCB in one module) rated for Type A residual current detection at 30 mA IΔn, with a B-curve thermal-magnetic overcurrent trip set at 20 A and a 4.5 kA breaking capacity. The 1+N-pole configuration protects a single phase and neutral, fitting standard 70 mm deep distribution boards. Type A detection covers sinusoidal AC and pulsating DC fault currents up to 6 mA smooth DC — the minimum for modern electronics-heavy loads like VFDs, switched-mode supplies, and EV chargers that a basic AC-type RCD would miss.
What the ratings mean on the panel
The B-curve at 20 A means the magnetic trip operates between 3 and 5 times rated current (60–100 A) — suited for resistive and general-purpose loads with moderate inrush, not motor starting. The 4.5 kA breaking capacity (Icn) is the short-circuit withstand under standard conditions per EN 60898; it handles domestic and light commercial fault levels. The 70 mm depth (D=70MM) fits flush in most European DIN-rail enclosures without door interference. The PSE/SSF marking indicates compliance with the Swedish PSE standard and the SSF (Swedish Fire Protection Association) requirements, relevant for installations in Sweden and Nordic markets.