The Siemens 5SU1353-6KV32 is an FI/LS protector combining Type A residual current protection and a B-curve miniature circuit breaker in a single 1+N-pole module, rated 32 A with 30 mA sensitivity and 4.5 kA breaking capacity.
Type A detection means it catches pulsating DC residual currents from rectified loads (VFDs, switched-mode supplies, LED drivers) — not just sinusoidal AC faults — so it's specified for circuits feeding modern electronics where standard AC-only RCDs would blind-trip or fail to trip. 30 mA IΔn is the standard personnel-protection threshold per IEC 60364; 4.5 kA breaking capacity covers residential and light commercial distribution boards fed by a transformer rated up to about 250 kVA. The B-curve (3-5 In magnetic trip) suits resistive and general-purpose loads with low inrush — lighting, socket circuits, small appliances. At 70 mm deep (D=70mm), it fits standard DIN-rail distribution boards without protruding past the enclosure cover — relevant when retrofitting into existing panels where wiring duct or gland-plate clearance is tight.
Snap-on DIN rail mounting, 1+N pole width (two modules wide). Neutral on the right, line on the left — verify busbar alignment if replacing a standard MCB-only position in an existing distribution board.