What the 1500W rating means on your rail
The 1.5SMC18A-M3/57T: That 59.5A peak current at the clamping voltage is the real protection envelope — if your fault source can deliver more than that, the TVS will fail short and you'll see the scorch mark on the board.
Package and temperature — where it survives
Housed in a DO-214AB (SMC) surface-mount package, the same footprint as the SMCJ series, so a rework station with a hot-air pencil set to 260°C for 10 seconds per joint will swap it cleanly. The operating junction temperature range spans -65°C to 150°C, which covers engine-bay ambient and industrial cabinet heat soak without derating the pulse power — the 1500W rating holds across that entire band. It is a single unidirectional channel, so it protects one DC rail polarity; for AC lines or bidirectional rails you would need two back-to-back or a bidirectional part.