I had a situation where a voltage spike occurred when the lithium batteries in my solar system finished charging, and the voltage spiked until the charge controller shut it off. This spike causes the inverter to shut down, necessitating a reset. I know that is what is going on because I caught it on my oscope. Currently, I have a TVS diode combined with a 22K uF elctrolytic cap across the lines from the charge controller, and that appears to work ok, but I am mystified as why it works. Either the TVS or the cap by themselves don't reliably prevent it. I saw the below circuit somewhere, and for the life of me, can't find the link now.
Anyway, the circuit is shown (hopefully) below. As I understand it, the R1 is there to limit current flow through the zener, and R2 is a 1 ohm inrush limiter to limit the current through the transistor to 30 amps max.
The nominal voltage is ~27-28 volts, and the zener voltage is 30 volts. My questions are, in no particular order:
1: Will this work?
2. What type of transistor would be best suited?
3: Is R3 necessary?