Obsolete — sourcing through independent channels
Littelfuse lists the 1.5KE150CA as Obsolete.
1500 W bidirectional transient suppressor
The 207 V clamp ceiling means this part protects a 128 V DC rail — the standoff is the continuous operating voltage the diode does not conduct at; above 143 V it starts to avalanche, and at 207 V it holds the line against the surge.
DO-201 axial package, industrial temperature range
The single bidirectional channel replaces two unidirectional diodes back-to-back in a single DO-201 body, saving board space on a 128 V rail that must survive both positive and negative transients.