For example, a reed relay matrix switch is normally switched with all contacts dry. After the contacts are all connected, a wire spring relay is energized and connects a supervisory scan point, or main switch, through which the primary current being controlled then flows. Dry contacts are primarily employed in extra-low voltage (less than 50 V AC) distribution circuits.
A reed relay matrix switch uses dry contacts for extra-low voltage (less than 50 V AC) distribution circuits. After connecting the contacts, a wire spring relay energizes and routes the primary current through a supervisory scan point or main switch.