The P6KE27ARL is listed as obsolete by STMicroelectronics.
600 W peak pulse — what it handles
This is a 600 W peak pulse power transient voltage suppressor from the ST P6KE TRANSIL™ series. It clamps at 48.3 V maximum when conducting its rated peak pulse current of 83 A under the 10/1000 µs waveform. The reverse standoff voltage is 23.1 V, meaning the part stays out of the circuit below that DC level and only starts conducting when a transient pushes the line above the 25.7 V minimum breakdown threshold. The single unidirectional channel makes it a straightforward fit for protecting a single DC rail or signal line against surges — typical for general-purpose industrial, telecom, or power-supply clamping where a through-hole axial part is acceptable.
DO-15 axial — the footprint it needs
The package is DO-204AC (DO-15) axial leaded, a standard through-hole form factor that inserts into a board or terminal strip and is wave-solder friendly. The 1150 pF typical capacitance at 1 MHz is worth noting for higher-frequency signal lines — it loads the line, so it is better suited to power rails or slower signals than to fast data buses. No power line protection rating is listed, which means it is intended for secondary-level transient suppression rather than direct mains clamping.