I wanted to control the power to a bridge rectifier. I had two ideas in my mind:
- Using a PCB mounted power relay driven by a transistor (is isolation maintained?)
- Using an SSR, i.e, a power triac driven by a optotriac, as shown below
In both cases, I would have to place a NTC thermistor to limit the inrush. The idea I chose was the SSR, which I haven't tested yet. But, someone told me:
Zero crossing will work for the first 1/4 cycle, but then:
- There will be no current flow to the "zero-volt switch" IC for it to know when the zero-cross happens, because "2200uF" is charged to 170V & all bridge diodes are reverse biased.
- Even if a firing pulse is given to triac @ zero-cross, it will not latch-on, because the available current is below "hold-on" current for Triac*
I would like to hear your viewpoints.