What the 1500W rating means for your rail
The 1.5KE480A/B: At the 658V clamp voltage, the 2.3A peak pulse current is the limit — push a bigger surge and the diode short-circuits, not opens, so the downstream gear sees the rail collapse instead of the spike. The 408V reverse standoff is the DC rail voltage it blocks without conducting. Above that, breakdown starts at 456V minimum, and the clamp hits 658V max at full rated current. Your 400V bus sits comfortably below standoff; a 480V bus is right at the edge and needs margin check.
Package and field-swap reality
DO-201AA / DO-27 axial leaded, through-hole. The body is big enough to read the marking without magnification — orientation is obvious because the cathode band is molded into the epoxy. You can swap it on site with a standard soldering iron and a solder sucker; no hot-air station needed. Operating temperature from -55°C to 150°C junction means it lives in the same environment as the rest of the power stage — no derating headache for outdoor or engine-bay use.