At 4 kW, the FSB frame crosses a thermal line. Below this rating — 2.2 kW at 96 W, 3 kW at 125.8 W — the FSB heatsink handles dissipation through natural convection alone. The 4 kW power stage generates 172.9 W of loss. That number breaks the convection-only thermal budget. The integrated fan (510–550 mA at 24 V DC) extends the enclosure depth from 134 mm to 169 mm and keeps the drive at full rated output in a +40 °C ambient.

Why does the 4 kW FSB threshold matter for conveyor design?

If your conveyor section runs near-full-load continuously — an incline belt with a constant product stream, or an accumulation zone that rarely idles — the fan-cooled FSB is not an option; it is the minimum viable thermal choice. The convection-cooled FSB ratings below 4 kW assume intermittent duty or cooler ambient temperatures. At 10.2 A continuous, the 175 Ω integrated braking resistor handles regenerative energy from frequent deceleration cycles without an external brake chopper. The 410 × 168 mm mounting pattern is the same as every FSB and FSC drive from 2.2 to 7.5 kW — the fan changes the depth, not the bolt pattern.