What the 1500W rating means on a TVS like this
The 1.5KE27A-TP: For a 23.1 V standoff rail, a 1500 W rating means it clamps a 40 A surge (Ipp) at 37.5 V, which is the voltage the protected circuit actually sees during the event.
Voltage thresholds and what they decide
Three numbers define where this part engages: reverse standoff is 23.1 V (normal operation — no leakage), breakdown starts at 25.7 V (where it begins conducting), and clamping max is 37.5 V at full peak current. A 24 V bus or a 24 VDC sensor supply sits below the standoff, so the TVS stays invisible until a surge pushes the rail above 25.7 V.
Package and field-swap reality
DO-201AE axial, through-hole — the same footprint as the common 1.5KE series. Two leads, polarity band on the cathode end. No orientation ambiguity: the banded end goes toward the rail being protected, the other to ground. Can be swapped on site with basic tools — no hot air, no reflow profile.
Temperature range for the full envelope
No derating needed at 85°C ambient; the 1500 W peak pulse figure holds across the band.