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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