What the 1500W rating means for your rail
The 1.5KE350A-T: The 300V reverse standoff voltage is the maximum continuous DC voltage the part blocks without conducting — your rail must stay at or below this level in steady state. When a surge hits, the device clamps at 482V max, shunting up to 4A of peak pulse current (10/1000µs waveform).
Through-hole axial package in DO-201AA / DO-27 form factor, with the supplier device package designated DO-201. The axial leads mount into plated through-holes on the PCB — the body sits above the board, so the hole spacing and lead bend radius must match the drawing. Tape & Reel packaging is the shipping format, not a reel-on-board option.
Lifecycle reality — obsolete, not a design-in
Diodes Incorporated lists the 1.5KE350A-T as Obsolete. This is not a part to spec into a new design.
Temperature and environment
Rated for continuous junction operation from -55°C to +175°C — the full industrial and military temperature band. The 175°C max junction temperature means the part handles high ambient heat in sealed enclosures or near hot components, as long as the PCB copper and airflow keep the junction below that ceiling.