1500 W peak pulse — the surge rating that defines the part
The 1N6150A: That 1.5 kW rating tells you the transient energy it can clamp before the junction fails — a common spec for secondary surge protection on DC rails where the upstream MOV or GDT handles the primary hit. Reverse standoff voltage is 16.7 V typical, with a minimum breakdown of 20.9 V and a maximum clamping voltage of 30.5 V at 49.2 A peak pulse current. The 16.7 V standoff means it sits across a 15 V or 16 V rail without conducting in normal operation, then clamps hard when a surge exceeds the breakdown threshold.
Microchip lists the 1N6150A as Active. For a storeroom or MRO inventory, this means you can order against a BOM line without stockpiling a lifetime buy — the part will be available for the next several years at least. The through-hole axial package (B, Axial) is a standard footprint that mates with existing PCB layouts and socket strips.
That covers military, avionics, and downhole environments where the ambient is hot and the transient energy adds self-heating. For a truck or bus application, confirm the temperature and surge requirements against the datasheet's peak pulse power derating curve.