Does Thyristor (SCR ) works for Inrush current protection?
I first saw a SCR employed to bypass some 5W wirewound green phillips resistors on the DC side of the mains bridge rectifier on a NZ designed SMPS in 1985 .The idea is that the resisters limited starting current charging the Phillips pcb mount        220 microfarad    385VDC elteclytic bus cap reasonably slowly .When the converter chip booted up the SCR turned on wasting about 1 Volt which was much better than just the resisters .Normal cheap TO220  SCRs do not have very good surge current ratings so reliability is not good where power quality is bad .A relay will waste less power and be more robust under surge conditions .30 years later I saw a triac on the AC side in a chinese imported SMPS .The AC Triac has the same shortcomings as the DC SCR .