Spectra Rms Molded Case Circuit Breakers (se150, Sf250, Sg600 And Sk1200) Havea Digital, Solid State, Rms Sensing Trip System With Field Installable, Front-mounted Rating Plugs To Establish Or Change The Breaker Ampere Rating. Adjustableinstantaneous With Tracking Short-time Is Standard On All Frames. The Trip System Uses Digital Sampling To Determine The Rms Value Of Sinusoidal And Non-sinusoidal Currents.