I have a converter board. working range is 80-250 VAC. i have cutoff range of 26VAC. when i start decreasing the voltage from 50 VAC input current is getting decreased, and suddenly increases again decreases. why this is happening?

 

May be because of very low power factor; not sure.

 

what is a converter board? please explain it, i am curious.

 

Converter board what i meant here is SMPS ( AC to DC converter)

 

But the common practice is -- rectifier : AC to DC, invertor : DC to AC, convertor : DC to (step-up or step-down) DC