A relay is an electrically operated switch, which has a control system (also known as the input circuit) and the controlled system (also known as the output circuit), usually used in automatic control circuit. It is actually "automatic switch", using a small electric current to control a larger current.Therefore, the relay has the effects on the automatical automatic adjustment, security, conversion circuit in the circuit and so on. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal.

The 16A relay module can be used in interactive projects. It can also be used to control the lighting, electrical and other equipments. It can be controlled through the digital IO port, such as solenoid valves, lamps, motors and other high current or high voltage devices. The main difference between 16A Relay module and the old version relay module is the Max switching current.The max switching current has been updated from 10A to 16A.