Obsolete — sourcing through independent channels
The 1.5KE400 is officially obsolete per Littelfuse.
Clamping and breakdown ratings for 342V rails
The 342 V reverse standoff means the diode draws negligible leakage below that rail voltage — it stays out of the circuit during normal operation and only conducts when a surge pushes the line above the breakdown threshold.
DO-201 axial package and temperature range
Housed in a DO-201AA (DO-27) axial-lead package, through-hole mounted. No power-line protection rating — this is a general-purpose transient suppressor for signal or DC bus protection, not for AC mains primary-side clamping.