Obsolete 1.5kW Zener TVS — sourcing reality
The 1.5KE91A-B: Diodes Incorporated lists this part as obsolete, so new production has ceased — availability is through independent surplus and broker channels, confirmed at RFQ time.
Clamping and standoff — what the ratings mean for your rail
The 77.8 V reverse standoff voltage is the maximum continuous DC voltage the TVS can sit across without conducting significantly — above that it starts to leak. For a nominal 72 V bus (common in telecom rectifiers or industrial DC supplies), the 77.8 V standoff provides enough margin to avoid false triggering during normal ripple, while the 125 V clamp stays below typical 100 V to 150 V semiconductor breakdown thresholds.