The Siemens 6SL3520-1XA24-0AF0 is the AS-Interface variant at 4 kW in the SINAMICS G115D distributed drive series, carrying the 1XA24 catalog designation in the 1XA2x sub-series. At 10.2 A rated and 20.4 A overload, this is the highest-power FSB drive — the ceiling of the FSB frame — with an integrated fan that extends continuous current capability beyond what natural convection alone can sustain.

Why does 4 kW FSB require a fan?

At 4 kW and 10.2 A rated, the FSB power stage dissipates more heat than the 425×180×134 mm enclosure can shed through natural convection alone. The integrated fan — adding 35 mm to the enclosure depth (169 vs 134 mm) and approximately 260 mA to the 24 V DC auxiliary load — enables continuous operation at full rated current up to 40°C ambient. Without the fan, the 4 kW FSB would require derating above approximately 3 kW continuous. This is the same thermal transition that occurs across all G115D catalog designations at 4 kW: XH24, XM04, XN04, XE04, XE44, 1XA04, and 1XA24 all share the same fan-cooled FSB hardware.

AS-Interface at 4 kW: the transition power

The 4 kW FSB sits at the transition between fanless FSB (2.2–3 kW) and FSC (5.5–7.5 kW). It powers medium-length conveyor sections — longer than a 3 kW zone can handle but not requiring the full 5.5 kW FSC capacity. The AF0 variant connects to the AS-Interface yellow flat cable, maintaining protocol consistency with the rest of the line. The 1XA24-0AF0 is mechanically identical to the 1XA04-0AF0 (1XA0x sub-series) — same hardware, parallel catalog code.