As is known, the switching capacity of relay contacts is determined by the area of contact surface, contact mass, contact force, and contact gap. The higher values that these parameters have, the higher the switching capacity of the contacts is. This is why powerful contacts differ from low-power ones, first of all in regard to their dimensions and second in regard to their gaps. A larger and more powerful coil is needed to create a large contact force and to move heavier contacts at a greater distance. Thus, one can state that for switching more powerful loads, a larger relay is needed (see Figure 5.1).