The SINAMICS G115D 6SL3520-2XB43-0AF0 is the PROFINET variant at 3 kW — the highest power rating in the G115D lineup cooled entirely by natural convection. It carries an NCNR (Not Suitable for New Designs) status. Unlike the 4 kW FSB which requires an integrated fan, this drive dissipates heat passively through the cast-aluminum housing, keeping the enclosure depth at 134 mm and eliminating the only moving part in the drive.

Why does the 3 kW FSB remain fanless?

At 3 kW, the IGBT switching losses are still within the thermal dissipation capacity of the FSB cast-aluminum enclosure under natural convection. No fan means no bearing wear, no dust ingress through fan openings, and lower 24 V DC control supply draw — approximately 250–290 mA compared to 510–550 mA for the fan-cooled 4 kW variant. For conveyor zones where the drive is mounted directly on the machine frame and exposed to vibration, eliminating the fan removes a mechanical failure point.

What changes at the step to 4 kW?

The adjacent 4 kW model (2XB44) introduces an integrated fan that extends the enclosure depth from 134 mm to 169 mm. The 35 mm depth increase and higher 24 V DC consumption are the only physical differences — the 425 × 180 mm mounting footprint is identical. For applications hovering at the 3–4 kW boundary, staying at 3 kW fanless may simplify the mechanical installation and control power budget if the power headroom is not needed.

How does the PROFINET variant differ from the I/O variant at 3 kW?

Both the AF0 and AB0 variants share the same 3 kW fanless power stage and FSB enclosure. The AF0 adds PROFINET with PROFIsafe and EtherNet/IP over M12 D-coded connectors with an integrated 2-port switch. The AB0 variant provides enhanced digital I/O with expanded STO via F-DI for applications where hardwired control is preferred.