The 1.5SMC33CA: For a storeroom or MRO inventory keeper, this part is still a standard stock item — no need to squirrel away a lifetime buy yet.
1500W peak pulse power — what it means for surge protection
That 1500 W rating is the energy-handling ceiling — below it the Zener junction absorbs the transient without failing short or open. The reverse standoff voltage of 28.2 V means the diode stays high-impedance below that level, so a 24 V rail sees no leakage penalty during normal operation. Breakdown occurs at 31.4 V minimum, giving a 3.2 V guard band before the TVS starts conducting.
Bidirectional channel — one part for both polarities
A single bidirectional channel protects against positive and negative transients on the same line. For AC signal lines or bipolar DC rails, this eliminates the need for two back-to-back unidirectional diodes and simplifies the PCB layout.