The Siemens 5SU1353-6KV25 is an FI/LS-protector — a combined residual current device (RCD) and miniature circuit breaker (MCB) in one DIN-rail module. It's a Type A RCD (sensitive to pulsating DC fault currents, as well as sinusoidal AC) paired with a B-curve MCB rated 25 A, in a 1+N-pole package.
Type A RCD means it's safe for circuits feeding single-phase electronics (VFDs, switch-mode power supplies) that generate pulsating DC leakage. The 30 mA IΔn is the standard for personal shock protection per IEC 60364. At 70 mm deep (D=70 mm) it fits standard distribution boards with no depth conflict.