What this RCBO is and where it fits
The Siemens 5SU1656-0KV13 is a combined residual-current circuit breaker with overcurrent protection (RCBO) — a single module that replaces a separate MCB and RCCD in a DIN-rail distribution board. It is a Type AC device, meaning it detects sinusoidal AC residual currents only; for pulsed DC or mixed-frequency faults you would need a Type A or Type F unit. The 300 mA sensitivity (IFN) is typical for fire-protection or whole-floor circuits rather than personal shock protection (which calls for 30 mA). The 6 kA breaking capacity suits domestic and light commercial TN systems where the prospective fault current stays below that threshold.
What the ratings mean for panel fit
The 70 mm width (D=70MM) occupies 4 standard DIN-rail modules (each 17.5 mm). The B-curve trips between 3 and 5 times rated current, so the 13 A rating clears fast on short circuits but tolerates the inrush of resistive loads and small lighting circuits. The 1+N-pole construction switches the line conductor and disconnects the neutral; the neutral pole is not switched in all RCBOs, so verify your distribution board's neutral bar arrangement — this unit expects the neutral to pass through the device.