An optocoupled relay with a TRIAC (3 KW max)
This circuit is very similar electromagnetic power relay.
It can turn on and off large loads, like furnaces, boiler, coocker, blower etc etc. I also works well with inductive loads such as asynchronous motors, transformers and large electromagnets.
By means of a “Zero crossing” photocoupler, the switching times are always at the precise moment of the passage of the zero (zero crossing). That means the commutations are clean, the electromagnetic interference are completely absent and do not develop dangerous extra voltage (spikes).
It can be used easily with Arduino system.