Thanks for the great explanation Korishan!For one, an AC breaker doesn't make much of a difference. The disconnect arc well self quench due to the alternating current
With DC, this is not the case. These breakers can be designed directional. Some of the circuitry in them may be directional. If there is a +/- (meaning Line/Load) or a diode symbol (denoting direction of flow) you need to wire them in that direction. Otherwise, it is possible the breaker will not trigger when it is supposed to (either too late, or too early)
With DC breakers, some of them have a current sense coil. If the coil is energized in the wrong direction, then it will not trigger the overcurrent protection and in fact keep it from working at all.
Not all DC breakers use a bi-metallic current trip strip. This is because DC creates a nasty current arc during heavy load disconnect and the contact pads need to be moved away from each other by distance and speed to quench the arc.
Another term these are called are "Polarized" breakers.
I am using that DC breaker in my system. Only polarity is marked, but no mention of direction...