TVSS products are intended to be placed at AC voltage inputs and outputs. Typically there is no change to the function on a daily basis, but in the event that the voltage difference between the power source and the protected line gets high enough, the switch closes and diverts the current away from the protected equipment. In combination with other protection equipment from your industrial equipment and data remains less susceptible to the damage that can be caused in an instant by a large power surge or over time from small ones.