Go Down

Topic: Circuit breaker ratings (Read 617 times) previous topic - next topic


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.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


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.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


Thanks for the replies. As it turns out, a 2A circuit breaker worked well, tripping in about a second after inducing locked rotor. - Scotty

Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131