What the 37.5 V clamp means on your rail
The 1.5KE27CA-T: When a transient hits, it clamps at 37.5 V maximum — that is the voltage the downstream silicon sees, not the 23.1 V standoff it was running at. If your 24 V rail's downstream parts are rated for 40 V or better, this clamp keeps them inside the safe operating area. Breakdown starts at 25.7 V minimum, so a sustained 24 V bus does not trigger it. The 40 A peak pulse current (Ipp) at the 37.5 V clamp tells you the energy it can dump before the part gives up — useful for sizing upstream fusing or PTCs.
DO-201 axial — the scorch-mark tells you
Through-hole DO-201AA (DO-27) axial package. The body is about 7.5 mm long with 0.050-inch diameter leads — standard for this power class. On a repair bench, a shorted TVS in this package leaves a telltale crack or discolouration on the body; the scorch mark tells you which rail took the hit before you even reach for the meter. The -T suffix means Tape & Reel packaging (also available as Cut Tape). For a one-off board repair, a Cut Tape quantity is the practical call; for a production run, the reel feeds an axial insertion machine without a feeder change.
Diodes Incorporated lists the 1.5KE27CA-T as Obsolete. No pin-compatible direct replacement from Diodes is documented, so a board spin is the only guaranteed path if you cannot source the original. Power line protection is not supported — this is a signal-rail or low-voltage bus protector, not a mains-side MOV replacement.