1. I need to make 200Vdc/5Adc SMPS from 220Vac/50Hz.
2. Its very high dc voltage. But I have 50Vdc/5A SMPS which has internal current limiting i.e if load ever tries to draw more than 5A from it, SMPS will go to CC mode.
3. can I connect 4 smps in series to make 200vdc/5A?
4. Can it work? What could be pitfalls? havent tried it myself as I dont know if something can went wrong?

 

I think it will work fine as long as it is never overloaded or, worse, shorted. The first one that shuts down will have current driven through its output in the wrong direction. What will happen in that situation depends on the particular design of the PSU and could probably be mitigated by having a reverse diode across each supply output to limit the reverse voltage.

 

found this, on page5, it explains.
https://www.google.co.in/url?sa=t&r...-0.pdf&usg=AFQjCNFvBIW2cYzsVKNrubM_SFPHYDjIFg