Safety instrumented system (SIS) for a turbine system

A retrofit kit (20) for a turbine system (10) is provided that includes a safety instrumented system (SIS) controller (18) having a first plurality of functions (108, 110) and the SIS controller (18) is configured to be coupled to a turbine-generator controller (16), wherein the SIS controller (18) permits a startup function of the turbine-generator controller (16) based on a plurality of inputs (76) from a turbine (12).