I got this at recycle centre. It appears to be a 3-phase rectifier bridge. But strange enough I could not find the datasheets for the two parts S20ZND06 and SC8K250ZD. Both have 3 poles each, +/~/- for S20ZND06, and K/C/A for SC8K250ZD. I believe S20ZND06 is a dual diode module. No idea what K/C/A are, though K or C probably Cathode and A Anode.
Also intriguing is that each pair of S20ZND06 and SC8K250ZD are connected in parallel +/K, ~/C, and -/C, which makes me think C probably stands for "Common". Easy to understand identical parts in parallel to have higher capacity or rating (though sometimes not that simple) but here two parts are not the same.
All the five terminals of the module behave the way as a 3-phase rectifier bridge does when testing with a multi meter.
Other than info about these two components, does anyone know the reason for such topology?