Velleman-Quad-Triac-Switch-Card-Electronics-Kit-Velleman-K2634-Extend-the-life-span-of-the-contact-points-in-your-relays-with-the-Velleman-Quad-Triac-Switch-Card-Kit-Relays-are-usually-used-to-switch-AC-voltages-by-means-of-an-electronic-control-but-when-switching-occurs-too-frequently-or-too-quickly-the-life-of-the-contact-points-is-shortened-considerably-This-can-be-solved-by-replacing-the-relays-with-a-triac-Using-opto-couplers-the-entire-interface-network-remains-electrically-isolate