The DIN‑Mountable VS861 Series Solid State Relay with an internal heat sink is the first complete solid state relay available in a modular package.A SSR (solid state relay) can perform many of the same tasks as an electromechanical relay.The SSR differs in that it contains no moving mechanical parts.It is essentially an electronic device that relies on the electrical,magnetic,and optical properties of semiconductors and electrical components to achieve its isolation and relay switching function.