A Solid State Relay is similar to a mechanic relay where it can be controlled through a digital signal. Solid State Relay generates no noise and has a much longer lifespan compared to the traditional mechanic relay.
This 5V 4-Channel SSR Solid State Relay Module 240V 2A Output with Resistive Fuse is based on the G3MB SSR relay which can control up to 2A at 240VAC. This is a 4 Channel SSR relay module, each relay channel has 3 separate terminals, NO (Normal Open), COM (Common), NC (Normal Closed).
When the input logic voltage is applied to the coil, the NC will disconnect from the COM breaking the conductivity between the two. At the same time, the NO will connect with the COM allowing conductivity between them. Depending on your wiring this will turn on or off the connected load.
1 x Solid State Relay Module G3MB-202P SSR (5V, 4-Channel)