What the 1500W rating means on the bench
The 1.5KE12CA-E3/54: For a 10.2 V reverse standoff rail, the clamping voltage hits 16.7 V at 89.8 A peak pulse current, so a 12 V supply bus sees the overvoltage chopped before it reaches downstream silicon. The bidirectional channel means it catches positive and negative transients equally — no polarity concern when you solder it into a DC rail or an AC signal line.
Through-hole DO-201AA (DO-27) axial package — the leads are 0.042-inch diameter and the body is about 9 mm long. The 1500 W rating assumes the leads are soldered into a PCB with adequate copper area to sink the heat; a free-air socket or long leads add inductance that shifts the clamping response.