1. Because power cables carry high currents, they generate magnetic fields around them. To prevent them from affecting other components, shielding layers are added to contain these electromagnetic fields within the cable.
2. They provide a certain degree of grounding protection. If the cable core is damaged, the leaked current can flow through the shielding layer and into the grounding grid, providing a safety barrier.
For control cables, there's no difference, except that in many places, especially computer system control cables, the shielding layer is used to block external influences. Because the current in these cables is very weak, they are very sensitive to external electromagnetic fields.
