1500 W of clamping — what the ratings mean on the bench
The 1.5SMC220A-E3/57T: That 1500 W figure is the product of the clamping voltage and the peak pulse current — here 328 V max clamp times 4.6 A peak pulse — so the part absorbs the surge energy by clamping the transient to 328 V before the downstream silicon sees it. The reverse standoff voltage is 185 V, meaning the diode stays off below that DC level and only starts conducting when the line voltage exceeds the breakdown threshold of 209 V min. This makes it a fit for 185 V nominal rails — think industrial DC buses or telecom supplies — where the TVS sits across the line and shunts transients without loading the rail during normal operation.
The product status is Active per Vishay's lifecycle record — no phase-out or last-time-buy notice on file.