APTINEX Four Channel Triac Module, is capable of controlling AC devices using its channels simultaneously with the aid of any microcontroller. Why would you choose a traic version over a relay? Traics have a longer lifetime than relays, as they are built of semiconductors. An optocouler is used in the module to provide isolation between high and low voltages. What protects the circuit when it is powered directly from the AC supply? MOV (metal-oxide vasristor) protection is used to protect against high voltage surges. A Voltage Snubber is also used for effective performance and device protection.