The intent and purpose of this document is to: (1) Establish a standard reference for determining and defining parameters needed to specify ac Solid State Relays (SSR) and Hybrid Solid State Relays (HSSR) which employ a single isolated input and are designed for switching of ac lines with maximums of 500 Hz in frequency@ 300 Vac in voltage and 50 amperes in current. (2) Develop uniform methods and techniques for measuring these parameters. This standard does not encompass relays that are designed for sensing or performing special logic (e.g. timers@ current or voltage sensors@ proximity switches@ etc.)@ In the case of conflict between this general standard and any individual standard or detail relay specification@ the individual specification shall govern. Several new classifications of relay types have been developed and standardized in recent years. These new types are distinguished primarily by the physical principles employed in their switching functions which have been made possible by utilization of solid state devices and technology. As a result@ four major relay groups (see definitions) are now considered to have industry-wide recognition and are listed below - although this standard proposes to cover only two of the four groups.