Thanks everyone. I was a bit confused about the breaker curves as well. I'm actually using these between a DC/DC converter and the devices being powered from it. Was hoping to protect the converter in the event of a short on one of the devices.
On Friday, December 28, 2018, Ken Hohhof <[email protected]> wrote: > Are you talking the AC or DC voltage rating? DC rating is usually lower, > because it is harder to quench the arc when opening the circuit if the > polarity doesn’t alternate. It’s usually difficult to find breakers with a > DC rating higher than 48 volts. But a higher voltage rating is not a > problem, just may cost a little more. > > > > You also need to look at the trip curve for the family of breakers. The > Altech/Sursum DIN rail breakers I usually use are not technically DC > breakers, but they come in a bazillion different trip curves, I usually buy > B or C. There will be a graph that shows the min/max trip time for various > percent current over rating. Usually that will take care of inrush unless > you have a load that has an unusually large or long lasting inrush. So > something between 1 and 2 times expected load. Let’s face it, if the load > is 1.7 amps, you aren’t going to have a 1.7 amp breaker in your stock of > breakers, maybe you have 2 and 5 amp breakers on hand. In that case I’d > probably go with the 2 amp, because 5 amps may not offer much protection, > especially since you probably have to get to 200% of rating for it to trip > quicky. The exception is any kind of DC UPS that draws extra current when > recharging the batteries, you need to allow for that, or everything will > seem fine until the first time you are recharging the batteries after a > power outage, and the circuit breaker trips after about 30 seconds. > > > > > > *From:* AF <[email protected]> *On Behalf Of *Jason McKemie > *Sent:* Friday, December 28, 2018 9:37 AM > *To:* AnimalFarm Microwave Users Group <[email protected]> > *Subject:* [AFMUG] DC Breakers > > > > Do you generally size these about double the expected load? > > > > I see a lot of them rated at higher voltages than I need, will these still > be effective? >
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