AC/DC Circuit Breakers
 

On Tue, 17 Jun 2003 11:54:29 GMT, "Geoffrey W. Schultz"
wrote:

I was standing in a marine store the other day looking at circuit breakers
and I suddenly perplexed by a lack of understanding. The breakers were all
labled with a max DC voltage, a max AC voltage and the breaker amp rating.
For example, a 10 amp breaker shows a max DC voltage of 65 V and a max AC
(50/60 cycle) voltage of 250V.

Will a 10 amp breaker work on 12 V DC as well as 120 V AC? I must admit
that I assumed that a 10 A 12V breaker would be equivalent to 1 A 120V
breaker. What am I missing? Anything?

Yes, it will. The reason it is more limited in DC VOLTAGE than AC
VOLTAGE is that AC goes through 0V, making any arcing duration only
part of a cycle, not a continuous flaming arc like DC can. 10A DC is
the same power as 10A RMS.....AT THE SAME VOLTAGE. Breakers don't
care what POWER you're running through them, only the CURRENT. The
load POWER output on 120VAC is 10X what 10A is at 12V.....1200 Watts
vs 120 Watts DC. The breaker doesn't feel the voltage...it's in
series.



Call me confused -- Geoff


Larry W4CSC

"No, NO, Mr Spock! I said beam me down a WRENCH,
not a WENCH! KIRK OUT!"