Three phase Solid State Relays (SSRs) have been available since shortly after the introduction of Single Phase SSRs in 1970. The first of these relays were nothing more than 3 individual SSRs with a common input connection packaged in a single housing. This basic design concept remains, for the most part, unchanged today. However, even though the function of single-phase and three phase relays are quite similar, their applications can vary significantly. This is primarily due to the characteristics of three phase power circuits and the attributes/ demands of three phase loads, particularly inductive loads. The proper selection and application of three phase SSRs for Motor control applications depends not only upon a comprehensive understanding of three phase SSRs, but also of the three phase power system and typical loads as well. This paper includes a summary review of three phase power systems, the characteristics of common three phase Motor loads, and a comprehensive discussion of three phase SSRs and their application relative to such loads.