Electronics > Projects, Designs, and Technical Stuff
Inrush current burns switches
Terry01:
I used these for the DPS5030 and they were fine.
http://www.ebay.co.uk/itm/231439337713
lordvader88:
OP aside from upgrading the switch, do u have any NTC in-rush limiting thermistors ? They work great, as far as I know so far. I have been using them with linear transformers, I'm worried about my big cap's blowing up.
Maybe for now if u could find 1 of those in an old TV or SMPS, and try for now with your switch. Also a temporary fix would be to make a milli-ohm resistor to put in series with the small switch.
Soon I will finally play with the relays I've gotton over the years from TVs etc. Now that will make a nice switch in a multi-PSU I'll put all in the same box.
wraper:
--- Quote from: lordvader88 on June 11, 2019, 11:17:46 pm ---OP aside from upgrading the switch, do u have any NTC in-rush limiting thermistors ? They work great, as far as I know so far. I have been using them with linear transformers, I'm worried about my big cap's blowing up.
--- End quote ---
Until you remove power and then switch ON again in a short period of time before NTC cools down.
Terry01:
Just looking at your schematic again... I put my switch on the AC + line between the mains AC 240v and the V+ on the PSU rather than between the PSU and the DPS5005.
I don't know if this is correct or not. Maybe one of the more experienced guys can give their opinion on this?
I am still learning too...
Siwastaja:
--- Quote from: wraper on June 11, 2019, 11:47:27 pm ---Until you remove power and then switch ON again in a short period of time before NTC cools down.
--- End quote ---
This. NTC is touted as an automatic inrush current limiter silver bullet on the forums, but it's a low-cost mass market solution which applies to a fairly small subset of inrush problems, and requires extensive analysis over edge cases to work reliably.
90% of the time, you want an actual inrush current limiting circuit, not an NTC. Whenever NTC happens to work, it's still a lot more than "just use an NTC".
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