The 1.5KE250C-E3/73: The 360 V clamping voltage at 4.2 A peak pulse current means a 202 V reverse standoff rail sees the clamp engage at 225 V breakdown minimum and hold the transient below 360 V — the margin between the rail and the clamp protects downstream silicon rated for 400 V or less. The single bidirectional channel handles positive and negative transients on the same line — no polarity concern during assembly.
Obsolete — sourcing through independent channels
Vishay lists the 1.5KE250C-/73 as Obsolete.