152 V rail protection — the clamp voltage that matters
That means the protected rail can sit at 152 V DC without the device conducting appreciably — the leakage stays low until the transient pushes above the 190 V minimum breakdown. When the transient hits, the diode clamps at 273 V maximum while passing a peak pulse current of 1.8 A under the 10/1000 µs waveform. The 500 W peak pulse power rating tells you the device can absorb that energy without failing — useful for sizing the protection on a 152 V DC bus or a 120 V AC signal line.
Microchip lists the 1N6137A as Active. The B Axial through-hole package is a standard leaded form factor — easy to hand-assemble, rework, or inspect. The wide range also gives thermal margin in high-ambient enclosures where the TVS self-heats during repetitive surges.
The base product number is 1N6137; the 'A' suffix indicates a specific breakdown voltage tolerance bin.