The
data sheet for the 120A breaker includes a curve showing trip level in % of rated current vs. time duration in seconds. The 'curve' is actually shown as a grey area ranging from mininum to maximum trip level; for example, the breaker will open after a 10 second surge of 200% to 330% of rated current, which corresponds to 240 to 400 Amperes. It will trip at lower currents that persist for longer durations. The 160 Ampere trip level that Cory mentioned corresponds to a duration of at least a minute, probably longer.
This helps explain why we rarely see the breaker trip. The
batteries we use are rated for 230A max. (5 second) surge current. Anything higher would be the result of a fault; i.e., a short circuit.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)