trešd., 2024. g. 7. aug., plkst. 00:21 — lietotājs Chris Albertson (<albertson.ch...@gmail.com>) rakstīja: > > The capacitor is charged when the switch is closed. A huge current will > flow into the capacitor until it is “full”. The usual solutions are to (1) > use a slow-blow fuse that can withstand the surge current or place a low > value power resister in series with the AC to limit maximum current. > Inductors can do this better than resistors. >
Yes, the inrush current that charges the capacitor is what I am thinking about now. I would prefer taking some ferrite ring and wrap the wire around it and be happy but I have no idea if that is how it works and I was not able to find any place to explain how to calculate. Initial values are: DC voltage is 340 V, current limit - hopefully around 10A, fuse is adjustable, originally set at 12 A (can be increased to 16 A). capacitor is 4700 uF. How do I calculate the time it takes to [almost] charge the capacitor? That would determine that transient state for inductor and then I have no idea how to calculate the inductor from here. I would prefer inductor because then there is nothing that can break. Input is 3 phase AC so I see following drawbacks with introducing resistors: 1) putting them after rectifier bridge seems like a violation of "no switches in DC bus" recommendation from 8i20 manual. Maybe except by having a resistor permanently connected in line and then having a SSR in parallel to resistor would be solution. But if SSR fails (I have experienced that) how will I know that? All load will go through resistor and burn it. 2) putting them in AC line requires 3 sets of that and the issue of the relay that bypasses resistor remains or have I missed something? It seems to me that 340V and approximately 10A would require 30-50 ohm resistor as suggested by Gene but somehow I am not sure 100W is enough. Or is it fine because it is very short period of time? Viesturs _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
