What the 1500W rating buys you on the rail
The 1.5KE130CA/B: That 1500W figure means it can absorb a transient energy pulse of that magnitude without failing short — the clamping voltage at that peak current is 179V max. For a 111V nominal rail, the standoff voltage sits below the line, so the diode stays out of the circuit during normal operation and only conducts when the surge pushes the rail above the breakdown threshold.
Bidirectional means one part covers both polarities
With a single bidirectional channel, this diode protects against positive and negative transients on the same line — no need to back-to-back two unidirectional parts. The package is rated for general-purpose applications — think power supplies, telecom lines, and industrial control inputs where a 111V rail needs transient clamping.