Hello All. I am working on a solar tracker using an automotive window regulator. I am using a current monitor in the system but as a last line of protection I plan on using a push-to-reset circuit breaker. I have one temporarily installed that's rated at 15A, 250vac. At a locked rotor current of 18.5 A, the circuit breaker doesn't trip. Must the breaker be rated for dc, 15A to function properly? Does it need to be rated at 12VDC? - Scotty
I think you want a DC rated breaker.
Circuit breakers generally have an inverse-time characteristic. For fast response (<1 second) you are typically looking at an overload of 5 to 10 times rating.
Your current of 1.8 times rating will typically take around 30 to 60 seconds for the trip to effect.
The type B breaker has the fastest trip characteristic but is still generally 2 to 3 times rating.
Breakers are rated by the current they carry reliably with no chance of breaking, so a 15A
breaker will usually carry 20A indefinitely (but might eventually trip), for instance. They are
to prevent short circuits melting the wiring, that's their main purpose, just like a fuse.
Thanks for the replies. As it turns out, a 2A circuit breaker worked well, tripping in about a second after inducing locked rotor. - Scotty