EM and SSR relays: Operation, differences and applications.
Application Note
To understand the basic operation of SSR relays (Solid State relay) and to differentiate them from electromechanical relays, as SSR's are products which use semiconductors and optical couplings, so there is no moving parts (therefore they are also known as static relays) and no inductive part in these products.
Thus, this document is divided into how solid-state relays work, which are the worldwide manufacturers of these products, applications of these products, comparative solid-state versus electromechanical relay technology, conclusion, and references.