The 1.5KE550A-B: The 760 V clamp voltage is the ceiling the downstream components see during a surge event. For a 480 VAC line (peak ~679 V), this TVS provides a clamp margin of about 80 V — enough to protect most semiconductor devices rated for 800 V or higher.
Through-hole DO-201 axial — board-fit and thermal path
Housed in a DO-201AA / DO-27 axial leaded package, the 1.5KE550A-B mounts through-hole and is suited for wave-solder or hand-solder assembly. The axial body allows the part to be laid flat against the board or stood off for better convection cooling — the junction temperature range spans -55 °C to 175 °C, so the thermal path through the leads and solder joints must handle the 1500 W pulse without exceeding the die temperature.