1500W transient suppressor — what it protects
It clamps voltage transients on DC power rails and signal lines in general-purpose industrial and telecom equipment.
The 1.5KE120ARL is listed as obsolete.
What the 1500W and 47A ratings mean for your board
The 1500W peak pulse power rating (10/1000µs) tells you the diode can absorb a 1.5 kW transient lasting one millisecond without failing — enough for typical surge events on a 100V bus in an industrial controller or a telecom line card. The 1000pF capacitance at 1MHz is moderate; it adds a small load on a signal line but is fine for DC power protection. The DO-201 axial package is through-hole, so it mounts into a drilled PCB or a terminal block — no reflow profile needed, but the leads need to be formed and inserted before wave soldering.