Survival rating for a 145V rail
The 1.5SMC170CA/TR13: Its 162V minimum breakdown voltage and 234V maximum clamping define the protection window: the rail rides safely below breakdown, and the clamp engages before the downstream silicon sees destructive overvoltage. The 6.5A peak pulse current at the clamp voltage tells you the energy it can absorb in a single event.
Bidirectional clamp, one package
That saves board area and simplifies the BOM for AC-coupled or floating signal lines where polarity is uncertain. The DO-214AB (SMC) package is a standard surface-mount footprint for 1500W-class TVS diodes. It reflows on a standard lead-free profile and the large copper tab on the bottom side conducts heat to the PCB pad — the junction temperature range spans -55°C to 150°C, covering outdoor and industrial enclosures.