7.4 Stored energy and the DC arc

Outcome 4 of 4 in domain 7 · Safety

Fuses, disconnects, cables and terminals up to the current.

My targets

I declare:

Calculate the energy stored in a pack and in a big capacitor, and translate it into what a short circuit releases.
Explain why a DC arc doesn’t go out on its own and why "DC" fuses and switches are different.
Choose the fuse of a pack or a 12 or 48 V system: rating, voltage rating, breaking capacity, and place it as close to the source as possible.
Size cables and terminals for peak current, and torque them: a loose terminal is a resistor that heats up.
Explain what a prospective short-circuit current is and why a 48 V pack delivers hundreds of amps.
Diagnosis: a blackened terminal or a melted connector on a pack, tightening, oxidation or gauge; what the voltage-drop-under-load measurement reveals.